21939723 has 48 divisors (see below), whose sum is σ = 36900864. Its totient is φ = 12450240.

The previous prime is 21939713. The next prime is 21939727. The reversal of 21939723 is 32793912.

It is not a de Polignac number, because 21939723 - 2⁵ = 21939691 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21939727) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 83290 + ... + 83552.

It is an arithmetic number, because the mean of its divisors is an integer number (768768).

Almost surely, 2^21939723 is an apocalyptic number.

21939723 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21939723 is a deficient number, since it is larger than the sum of its proper divisors (14961141).

21939723 is a wasteful number, since it uses less digits than its factorization.

21939723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336 (or 333 counting only the distinct ones).

The product of its digits is 20412, while the sum is 36.

The square root of 21939723 is about 4683.9858027112. The cubic root of 21939723 is about 279.9477921368.

The spelling of 21939723 in words is "twenty-one million, nine hundred thirty-nine thousand, seven hundred twenty-three".