21390964 has 24 divisors (see below), whose sum is σ = 45299520. Its totient is φ = 8628096.

The previous prime is 21390911. The next prime is 21390977. The reversal of 21390964 is 46909312.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21994 + ... + 22945.

It is an arithmetic number, because the mean of its divisors is an integer number (1887480).

Almost surely, 2^21390964 is an apocalyptic number.

It is an amenable number.

21390964 is an abundant number, since it is smaller than the sum of its proper divisors (23908556).

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

21390964 is a wasteful number, since it uses less digits than its factorization.

21390964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44967 (or 44965 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 21390964 is about 4625.0366485034. The cubic root of 21390964 is about 277.5940281418.

The spelling of 21390964 in words is "twenty-one million, three hundred ninety thousand, nine hundred sixty-four".