21564275 has 6 divisors (see below), whose sum is σ = 26739732. Its totient is φ = 17251400.

The previous prime is 21564247. The next prime is 21564289. The reversal of 21564275 is 57246512.

It is not a de Polignac number, because 21564275 - 2²⁰ = 20515699 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 431261 + ... + 431310.

It is an arithmetic number, because the mean of its divisors is an integer number (4456622).

Almost surely, 2^21564275 is an apocalyptic number.

21564275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21564275 is a deficient number, since it is larger than the sum of its proper divisors (5175457).

21564275 is an equidigital number, since it uses as much as digits as its factorization.

21564275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862581 (or 862576 counting only the distinct ones).

The product of its digits is 16800, while the sum is 32.

The square root of 21564275 is about 4643.7350268938. The cubic root of 21564275 is about 278.3417075500.

The spelling of 21564275 in words is "twenty-one million, five hundred sixty-four thousand, two hundred seventy-five".