21638232 has 128 divisors (see below), whose sum is σ = 74995200. Its totient is φ = 5616000.

The previous prime is 21638231. The next prime is 21638249. The reversal of 21638232 is 23283612.

21638232 is a `hidden beast` number, since 2 + 1 + 638 + 23 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21638196 and 21638205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21638231) 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, 15982 + ... + 17282.

It is an arithmetic number, because the mean of its divisors is an integer number (585900).

Almost surely, 2^21638232 is an apocalyptic number.

21638232 is a gapful number since it is divisible by the number (22) 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 21638232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37497600).

21638232 is an abundant number, since it is smaller than the sum of its proper divisors (53356968).

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

21638232 is a wasteful number, since it uses less digits than its factorization.

21638232 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1334 (or 1324 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 21638232 is about 4651.6913053211. The cubic root of 21638232 is about 278.6595454125.

The spelling of 21638232 in words is "twenty-one million, six hundred thirty-eight thousand, two hundred thirty-two".