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21632 = 27132

21632 has 24 divisors (see below), whose sum is σ = 46665. Its totient is φ = 9984.

The previous prime is 21617. The next prime is 21647. The reversal of 21632 is 23612.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is an interprime number because it is at equal distance from previous prime (21617) and next prime (21647).

It can be written as a sum of positive squares in 2 ways, for example, as 18496 + 3136 = 136^2 + 56^2 .

It is an ABA number since it can be written as A⋅BA, here for A=2, B=104.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a nialpdrome in base 8 and base 15.

It is a zygodrome in base 15.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1658 + ... + 1670.

221632 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21632

21632 is an abundant number, since it is smaller than the sum of its proper divisors (25033).

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

21632 is an equidigital number, since it uses as much as digits as its factorization.

21632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40 (or 15 counting only the distinct ones).

The product of its digits is 72, while the sum is 14.

The square root of 21632 is about 147.0782104868. The cubic root of 21632 is about 27.8632790715.

Multiplying 21632 by its product of digits (72), we get a square (1557504 = 12482).

The spelling of 21632 in words is "twenty-one thousand, six hundred thirty-two".

Divisors: 1 2 4 8 13 16 26 32 52 64 104 128 169 208 338 416 676 832 1352 1664 2704 5408 10816 21632