21634880 has 112 divisors (see below), whose sum is σ = 56455056. Its totient is φ = 7864320.

The previous prime is 21634871. The next prime is 21634909. The reversal of 21634880 is 8843612.

It can be written as a sum of positive squares in 8 ways, for example, as 1132096 + 20502784 = 1064^2 + 4528^2 .

It is a super-2 number, since 2×21634880² = 936136065228800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 222992 + ... + 223088.

It is an arithmetic number, because the mean of its divisors is an integer number (504063).

Almost surely, 2^21634880 is an apocalyptic number.

21634880 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 21634880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28227528).

21634880 is an abundant number, since it is smaller than the sum of its proper divisors (34820176).

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

21634880 is a wasteful number, since it uses less digits than its factorization.

21634880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172 (or 162 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 21634880 is about 4651.3309923075. The cubic root of 21634880 is about 278.6451555271.

The spelling of 21634880 in words is "twenty-one million, six hundred thirty-four thousand, eight hundred eighty".