21791908 has 6 divisors (see below), whose sum is σ = 38135846. Its totient is φ = 10895952.

The previous prime is 21791897. The next prime is 21791911. The reversal of 21791908 is 80919712.

It can be written as a sum of positive squares in only one way, i.e., 18249984 + 3541924 = 4272^2 + 1882^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2723985 + ... + 2723992.

Almost surely, 2^21791908 is an apocalyptic number.

It is an amenable number.

21791908 is a deficient number, since it is larger than the sum of its proper divisors (16343938).

21791908 is a wasteful number, since it uses less digits than its factorization.

21791908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5447981 (or 5447979 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 21791908 is about 4668.1803735503. The cubic root of 21791908 is about 279.3176753463.

The spelling of 21791908 in words is "twenty-one million, seven hundred ninety-one thousand, nine hundred eight".