21845920 has 24 divisors (see below), whose sum is σ = 51611364. Its totient is φ = 8738304.

The previous prime is 21845909. The next prime is 21845959. The reversal of 21845920 is 2954812.

It can be written as a sum of positive squares in 2 ways, for example, as 21790224 + 55696 = 4668^2 + 236^2 .

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, 68109 + ... + 68428.

Almost surely, 2^21845920 is an apocalyptic number.

21845920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21845920 is an abundant number, since it is smaller than the sum of its proper divisors (29765444).

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

21845920 is a wasteful number, since it uses less digits than its factorization.

21845920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136552 (or 136544 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 21845920 is about 4673.9619168324. The cubic root of 21845920 is about 279.5482511373.

The spelling of 21845920 in words is "twenty-one million, eight hundred forty-five thousand, nine hundred twenty".