21563628 has 24 divisors (see below), whose sum is σ = 50495088. Its totient is φ = 7162176.

The previous prime is 21563611. The next prime is 21563639. The reversal of 21563628 is 82636512.

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, 450 + ... + 6582.

It is an arithmetic number, because the mean of its divisors is an integer number (2103962).

Almost surely, 2^21563628 is an apocalyptic number.

It is an amenable number.

21563628 is an abundant number, since it is smaller than the sum of its proper divisors (28931460).

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

21563628 is a wasteful number, since it uses less digits than its factorization.

21563628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6433 (or 6431 counting only the distinct ones).

The product of its digits is 17280, while the sum is 33.

The square root of 21563628 is about 4643.6653626204. The cubic root of 21563628 is about 278.3389237964.

The spelling of 21563628 in words is "twenty-one million, five hundred sixty-three thousand, six hundred twenty-eight".