21657852 has 18 divisors (see below), whose sum is σ = 54746328. Its totient is φ = 7219272.

The previous prime is 21657833. The next prime is 21657863. The reversal of 21657852 is 25875612.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 601607 = 21657852 / (2 + 1 + 6 + 5 + 7 + 8 + 5 + 2).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 300768 + ... + 300839.

Almost surely, 2^21657852 is an apocalyptic number.

It is an amenable number.

21657852 is an abundant number, since it is smaller than the sum of its proper divisors (33088476).

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

21657852 is a wasteful number, since it uses less digits than its factorization.

21657852 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601617 (or 601612 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 21657852 is about 4653.7997378486. The cubic root of 21657852 is about 278.7437428130.

The spelling of 21657852 in words is "twenty-one million, six hundred fifty-seven thousand, eight hundred fifty-two".