21266290 has 16 divisors (see below), whose sum is σ = 39213720. Its totient is φ = 8298880.

The previous prime is 21266239. The next prime is 21266291. The reversal of 21266290 is 9266212.

It can be written as a sum of positive squares in 4 ways, for example, as 6985449 + 14280841 = 2643^2 + 3779^2 .

It is not an unprimeable number, because it can be changed into a prime (21266291) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25525 + ... + 26344.

Almost surely, 2^21266290 is an apocalyptic number.

21266290 is a deficient number, since it is larger than the sum of its proper divisors (17947430).

21266290 is a wasteful number, since it uses less digits than its factorization.

21266290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51917.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21266290 is about 4611.5387887342. The cubic root of 21266290 is about 277.0536720405.

The spelling of 21266290 in words is "twenty-one million, two hundred sixty-six thousand, two hundred ninety".