21552817 has 16 divisors (see below), whose sum is σ = 26425728. Its totient is φ = 17297280.

The previous prime is 21552799. The next prime is 21552823. The reversal of 21552817 is 71825512.

It is a de Polignac number, because none of the positive numbers 2^k-21552817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21552317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13 + ... + 6565.

It is an arithmetic number, because the mean of its divisors is an integer number (1651608).

Almost surely, 2^21552817 is an apocalyptic number.

It is an amenable number.

21552817 is a deficient number, since it is larger than the sum of its proper divisors (4872911).

21552817 is a wasteful number, since it uses less digits than its factorization.

21552817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6600.

The product of its digits is 5600, while the sum is 31.

The square root of 21552817 is about 4642.5011577812. The cubic root of 21552817 is about 278.2924006244.

The spelling of 21552817 in words is "twenty-one million, five hundred fifty-two thousand, eight hundred seventeen".