21730864 has 10 divisors (see below), whose sum is σ = 42103580. Its totient is φ = 10865424.

The previous prime is 21730853. The next prime is 21730871. The reversal of 21730864 is 46803712.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 679074 + ... + 679105.

It is an arithmetic number, because the mean of its divisors is an integer number (4210358).

Almost surely, 2^21730864 is an apocalyptic number.

It is an amenable number.

21730864 is a deficient number, since it is larger than the sum of its proper divisors (20372716).

21730864 is a wasteful number, since it uses less digits than its factorization.

21730864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1358187 (or 1358181 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 21730864 is about 4661.6374805426. The cubic root of 21730864 is about 279.0566210457.

The spelling of 21730864 in words is "twenty-one million, seven hundred thirty thousand, eight hundred sixty-four".