21638160 has 120 divisors (see below), whose sum is σ = 74542104. Its totient is φ = 5621760.

The previous prime is 21638153. The next prime is 21638167. The reversal of 21638160 is 6183612.

21638160 is a `hidden beast` number, since 21 + 638 + 1 + 6 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21638153) and next prime (21638167).

It can be written as a sum of positive squares in 4 ways, for example, as 2663424 + 18974736 = 1632^2 + 4356^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21638167) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29154 + ... + 29886.

Almost surely, 2^21638160 is an apocalyptic number.

21638160 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 21638160, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37271052).

21638160 is an abundant number, since it is smaller than the sum of its proper divisors (52903944).

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

21638160 is a wasteful number, since it uses less digits than its factorization.

21638160 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 793 (or 784 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21638160 is about 4651.6835661941. The cubic root of 21638160 is about 278.6592363375.

The spelling of 21638160 in words is "twenty-one million, six hundred thirty-eight thousand, one hundred sixty".