21166788 has 36 divisors (see below), whose sum is σ = 50226288. Its totient is φ = 6937920.

The previous prime is 21166787. The next prime is 21166799. The reversal of 21166788 is 88766112.

It is not an unprimeable number, because it can be changed into a prime (21166787) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 63783 + ... + 64113.

Almost surely, 2^21166788 is an apocalyptic number.

It is an amenable number.

21166788 is an abundant number, since it is smaller than the sum of its proper divisors (29059500).

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

21166788 is a wasteful number, since it uses less digits than its factorization.

21166788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484 (or 409 counting only the distinct ones).

The product of its digits is 32256, while the sum is 39.

The square root of 21166788 is about 4600.7377669239. The cubic root of 21166788 is about 276.6208978982.

The spelling of 21166788 in words is "twenty-one million, one hundred sixty-six thousand, seven hundred eighty-eight".