21723937 has 4 divisors (see below), whose sum is σ = 22668480. Its totient is φ = 20779396.

The previous prime is 21723931. The next prime is 21723959. The reversal of 21723937 is 73932712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-21723937 is a prime.

It is a pancake number, because a pancake can be divided into 21723937 parts by 6591 straight cuts.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21723931) 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 3 ways as a sum of consecutive naturals, for example, 472237 + ... + 472282.

It is an arithmetic number, because the mean of its divisors is an integer number (5667120).

Almost surely, 2^21723937 is an apocalyptic number.

It is an amenable number.

21723937 is a deficient number, since it is larger than the sum of its proper divisors (944543).

21723937 is an equidigital number, since it uses as much as digits as its factorization.

21723937 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 944542.

The product of its digits is 15876, while the sum is 34.

The square root of 21723937 is about 4660.8944420572. The cubic root of 21723937 is about 279.0269668996.

The spelling of 21723937 in words is "twenty-one million, seven hundred twenty-three thousand, nine hundred thirty-seven".