21364920 has 96 divisors (see below), whose sum is σ = 73541520. Its totient is φ = 5360640.

The previous prime is 21364919. The next prime is 21364939. The reversal of 21364920 is 2946312.

21364920 is a `hidden beast` number, since 2 + 13 + 649 + 2 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4375 + ... + 7865.

Almost surely, 2^21364920 is an apocalyptic number.

21364920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21364920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36770760).

21364920 is an abundant number, since it is smaller than the sum of its proper divisors (52176600).

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

21364920 is a wasteful number, since it uses less digits than its factorization.

21364920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3525 (or 3518 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21364920 is about 4622.2202457261. The cubic root of 21364920 is about 277.4813233108.

It can be divided in two parts, 2136 and 4920, that added together give a square (7056 = 84²).

The spelling of 21364920 in words is "twenty-one million, three hundred sixty-four thousand, nine hundred twenty".