21912537 has 16 divisors (see below), whose sum is σ = 30643200. Its totient is φ = 13901712.

The previous prime is 21912521. The next prime is 21912563. The reversal of 21912537 is 73521912.

It is not a de Polignac number, because 21912537 - 2⁴ = 21912521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21912577) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14964 + ... + 16362.

It is an arithmetic number, because the mean of its divisors is an integer number (1915200).

Almost surely, 2^21912537 is an apocalyptic number.

It is an amenable number.

21912537 is a deficient number, since it is larger than the sum of its proper divisors (8730663).

21912537 is a wasteful number, since it uses less digits than its factorization.

21912537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1652.

The product of its digits is 3780, while the sum is 30.

The square root of 21912537 is about 4681.0828875379. The cubic root of 21912537 is about 279.8321144935.

The spelling of 21912537 in words is "twenty-one million, nine hundred twelve thousand, five hundred thirty-seven".