21852921 has 32 divisors (see below), whose sum is σ = 32117760. Its totient is φ = 13172544.

The previous prime is 21852913. The next prime is 21852947. The reversal of 21852921 is 12925812.

It is not a de Polignac number, because 21852921 - 2³ = 21852913 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21852911) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 133986 + ... + 134148.

It is an arithmetic number, because the mean of its divisors is an integer number (1003680).

Almost surely, 2^21852921 is an apocalyptic number.

It is an amenable number.

21852921 is a deficient number, since it is larger than the sum of its proper divisors (10264839).

21852921 is a wasteful number, since it uses less digits than its factorization.

21852921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285.

The product of its digits is 2880, while the sum is 30.

The square root of 21852921 is about 4674.7107931935. The cubic root of 21852921 is about 279.5781103860.

The spelling of 21852921 in words is "twenty-one million, eight hundred fifty-two thousand, nine hundred twenty-one".