21791166 has 16 divisors (see below), whose sum is σ = 45477504. Its totient is φ = 6947864.

The previous prime is 21791149. The next prime is 21791173. The reversal of 21791166 is 66119712.

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, 78816 + ... + 79091.

It is an arithmetic number, because the mean of its divisors is an integer number (2842344).

Almost surely, 2^21791166 is an apocalyptic number.

21791166 is an abundant number, since it is smaller than the sum of its proper divisors (23686338).

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

21791166 is a wasteful number, since it uses less digits than its factorization.

21791166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157935.

The product of its digits is 4536, while the sum is 33.

The square root of 21791166 is about 4668.1008986525. The cubic root of 21791166 is about 279.3145051165.

The spelling of 21791166 in words is "twenty-one million, seven hundred ninety-one thousand, one hundred sixty-six".