21729952 has 24 divisors (see below), whose sum is σ = 43939476. Its totient is φ = 10570752.

The previous prime is 21729941. The next prime is 21729971. The reversal of 21729952 is 25992712.

It can be written as a sum of positive squares in 2 ways, for example, as 21566736 + 163216 = 4644^2 + 404^2 .

It is a Harshad number since it is a multiple of its sum of digits (37).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7993 + ... + 10360.

Almost surely, 2^21729952 is an apocalyptic number.

It is an amenable number.

21729952 is an abundant number, since it is smaller than the sum of its proper divisors (22209524).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21729952 is a wasteful number, since it uses less digits than its factorization.

21729952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18400 (or 18392 counting only the distinct ones).

The product of its digits is 22680, while the sum is 37.

The square root of 21729952 is about 4661.5396598120. The cubic root of 21729952 is about 279.0527171788.

The spelling of 21729952 in words is "twenty-one million, seven hundred twenty-nine thousand, nine hundred fifty-two".