21625644 has 12 divisors (see below), whose sum is σ = 50459864. Its totient is φ = 7208544.

The previous prime is 21625633. The next prime is 21625661. The reversal of 21625644 is 44652612.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 901057 + ... + 901080.

Almost surely, 2^21625644 is an apocalyptic number.

It is an amenable number.

21625644 is an abundant number, since it is smaller than the sum of its proper divisors (28834220).

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

21625644 is a wasteful number, since it uses less digits than its factorization.

21625644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1802144 (or 1802142 counting only the distinct ones).

The product of its digits is 11520, while the sum is 30.

The square root of 21625644 is about 4650.3380522280. The cubic root of 21625644 is about 278.6054983783.

The spelling of 21625644 in words is "twenty-one million, six hundred twenty-five thousand, six hundred forty-four".