21332646 has 40 divisors (see below), whose sum is σ = 49106640. Its totient is φ = 6916752.

The previous prime is 21332629. The next prime is 21332651. The reversal of 21332646 is 64623312.

21332646 is a `hidden beast` number, since 2 + 13 + 3 + 2 + 646 = 666.

It is a super-2 number, since 2×21332646² = 910163570722632, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4215 + ... + 7773.

It is an arithmetic number, because the mean of its divisors is an integer number (1227666).

Almost surely, 2^21332646 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21332646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24553320).

21332646 is an abundant number, since it is smaller than the sum of its proper divisors (27773994).

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

21332646 is a wasteful number, since it uses less digits than its factorization.

21332646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3610 (or 3601 counting only the distinct ones).

The product of its digits is 5184, while the sum is 27.

The square root of 21332646 is about 4618.7277469017. The cubic root of 21332646 is about 277.3415311438.

Adding to 21332646 its reverse (64623312), we get a palindrome (85955958).

The spelling of 21332646 in words is "twenty-one million, three hundred thirty-two thousand, six hundred forty-six".