21164255 has 32 divisors (see below), whose sum is σ = 30855168. Its totient is φ = 13622400.

The previous prime is 21164239. The next prime is 21164281. The reversal of 21164255 is 55246112.

It is not a de Polignac number, because 21164255 - 2⁴ = 21164239 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48890 + ... + 49320.

It is an arithmetic number, because the mean of its divisors is an integer number (964224).

Almost surely, 2^21164255 is an apocalyptic number.

21164255 is a deficient number, since it is larger than the sum of its proper divisors (9690913).

21164255 is a wasteful number, since it uses less digits than its factorization.

21164255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527.

The product of its digits is 2400, while the sum is 26.

The square root of 21164255 is about 4600.4624767517. The cubic root of 21164255 is about 276.6098631790.

The spelling of 21164255 in words is "twenty-one million, one hundred sixty-four thousand, two hundred fifty-five".