21566116 has 48 divisors (see below), whose sum is σ = 45581760. Its totient is φ = 8795520.

The previous prime is 21566101. The next prime is 21566117. The reversal of 21566116 is 61166512.

It is not an unprimeable number, because it can be changed into a prime (21566117) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20655 + ... + 21673.

It is an arithmetic number, because the mean of its divisors is an integer number (949620).

Almost surely, 2^21566116 is an apocalyptic number.

21566116 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21566116 is an abundant number, since it is smaller than the sum of its proper divisors (24015644).

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

21566116 is a wasteful number, since it uses less digits than its factorization.

21566116 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1084 (or 1082 counting only the distinct ones).

The product of its digits is 2160, while the sum is 28.

The square root of 21566116 is about 4643.9332467209. The cubic root of 21566116 is about 278.3496282507.

The spelling of 21566116 in words is "twenty-one million, five hundred sixty-six thousand, one hundred sixteen".