21565716 has 24 divisors (see below), whose sum is σ = 50408064. Its totient is φ = 7176000.

The previous prime is 21565699. The next prime is 21565721. The reversal of 21565716 is 61756512.

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, 7816 + ... + 10208.

It is an arithmetic number, because the mean of its divisors is an integer number (2100336).

Almost surely, 2^21565716 is an apocalyptic number.

It is an amenable number.

21565716 is an abundant number, since it is smaller than the sum of its proper divisors (28842348).

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

21565716 is a wasteful number, since it uses less digits than its factorization.

21565716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3151 (or 3149 counting only the distinct ones).

The product of its digits is 12600, while the sum is 33.

The square root of 21565716 is about 4643.8901795800. The cubic root of 21565716 is about 278.3479073329.

The spelling of 21565716 in words is "twenty-one million, five hundred sixty-five thousand, seven hundred sixteen".