21564402 has 8 divisors (see below), whose sum is σ = 43128816. Its totient is φ = 7188132.

The previous prime is 21564397. The next prime is 21564407. The reversal of 21564402 is 20446512.

It is an interprime number because it is at equal distance from previous prime (21564397) and next prime (21564407).

It is a sphenic number, since it is the product of 3 distinct primes.

21564402 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21564407) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1797028 + ... + 1797039.

It is an arithmetic number, because the mean of its divisors is an integer number (5391102).

Almost surely, 2^21564402 is an apocalyptic number.

21564402 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21564402 is a wasteful number, since it uses less digits than its factorization.

21564402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3594072.

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 21564402 is about 4643.7487012111. The cubic root of 21564402 is about 278.3422539681.

The spelling of 21564402 in words is "twenty-one million, five hundred sixty-four thousand, four hundred two".