Java

#259797

A cyan that is muted. It is light — black text sits on it comfortably, white text does not.

Hex

#259797

RGB

37, 151, 151

OKLCh

61.7% 0.096 194.9°

CIELAB (D50)

56.6, -31.5, -9.5

What is true of this colour, and of no other

7 other named colours sit within ΔE00 2 of it.
It uses 92% of the chroma sRGB can show at this lightness and hue — close enough to the boundary that a wider display would show it slightly more vividly.
As text on white it measures APCA Lc 62.5; on black, Lc -39.2. The sign is the polarity, which the WCAG ratio discards.
Built into an eleven-step scale, 10 of the 10 adjacent pairs stay ΔE00 2 apart — see the ramp.
protanopia and deuteranopia and tritanopia shift it by ΔE00 24.3 and 25.6 and 33.4 — no red cone.

Text on this colour

White text

3.53:1 — large text only

Black text

5.95:1 — passes AA

Black text is the better of the two at5.95:1. That is enough for body text.

As text on white, it needs to change

#008585 is the nearest colour of the same hue that passes AA on white, at 4.50:1. Only the lightness moved, and some saturation was given up to stay inside sRGB.

Try it against your own background

The same colour, with one cone missing

As you see it

#259797

protanopia

#8f8f97 · ΔE00 24.3

deuteranopia

#828298 · ΔE00 25.6

tritanopia

#7171ff · ΔE00 33.4

Run a whole palette through all three

The twelve nearest named colours

Ranked by CIEDE2000 — perceptual distance, not hex arithmetic. The closest isSea Fantasy at ΔE00 1.084: between 1 and 2 — a trained eye spots it when the two touch; nobody spots it across a room. What the numbers mean.

Sea FantasyΔE00 1.084 · #1a9597
Ocean ReefΔE00 1.175 · #1f989b
Regula Barbara BlueΔE00 1.272 · #009999
AtrovirensΔE00 1.439 · #0d9494
IntermezzoΔE00 1.567 · #019694
Paradise LandscapeΔE00 1.641 · #009494
Riviera ParadiseΔE00 1.92 · #009a9e
BalticΔE00 2.126 · #279d9f
Lido DeckΔE00 2.189 · #019294
Empress EnvyΔE00 2.328 · #2a9ca0
ColumbiaΔE00 2.38 · #009792
Common TealΔE00 2.491 · #009193

11 of these have no page of their own: pages exist for the 4,961 colours the dataset marks as good names.