21544985 has 32 divisors (see below), whose sum is σ = 32596992. Its totient is φ = 13279680.

The previous prime is 21544979. The next prime is 21544987. The reversal of 21544985 is 58944512.

It is not a de Polignac number, because 21544985 - 2¹⁰ = 21543961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21544987) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40934 + ... + 41456.

It is an arithmetic number, because the mean of its divisors is an integer number (1018656).

Almost surely, 2^21544985 is an apocalyptic number.

It is an amenable number.

21544985 is a deficient number, since it is larger than the sum of its proper divisors (11052007).

21544985 is a wasteful number, since it uses less digits than its factorization.

21544985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 653.

The product of its digits is 57600, while the sum is 38.

The square root of 21544985 is about 4641.6575703083. The cubic root of 21544985 is about 278.2586873184.

The spelling of 21544985 in words is "twenty-one million, five hundred forty-four thousand, nine hundred eighty-five".