86

86 = 2 x 43.

86 is conjectured to be the largest number n such that 2ⁿ (in decimal) doesn't contain a 0.

86 is 222 in base 6.

86 arises in the sequence generated by starting with 1, then adding 4 and reversing the digits to get the next term: 1, 5, 9, 13, 35, 57, . . . , 28, 86, 72, . . .

86 is the atomic number of radon.

In the TV series and movie Get Smart, the principal character Maxwell Smart was known as Agent 86.

Source: Number Gossip