21086259 has 16 divisors (see below), whose sum is σ = 28957824. Its totient is φ = 13640000.

The previous prime is 21086251. The next prime is 21086279. The reversal of 21086259 is 95268012.

It is a cyclic number.

It is not a de Polignac number, because 21086259 - 2³ = 21086251 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21086251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30532 + ... + 31214.

It is an arithmetic number, because the mean of its divisors is an integer number (1809864).

Almost surely, 2^21086259 is an apocalyptic number.

21086259 is a deficient number, since it is larger than the sum of its proper divisors (7871565).

21086259 is a wasteful number, since it uses less digits than its factorization.

21086259 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 978.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21086259 is about 4591.9776785172. The cubic root of 21086259 is about 276.2696508751.

The spelling of 21086259 in words is "twenty-one million, eighty-six thousand, two hundred fifty-nine".