21556746 has 32 divisors (see below), whose sum is σ = 48055680. Its totient is φ = 7162848.

The previous prime is 21556739. The next prime is 21556753. The reversal of 21556746 is 64765512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21556739) and next prime (21556753).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21556746.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32995 + ... + 33641.

It is an arithmetic number, because the mean of its divisors is an integer number (1501740).

Almost surely, 2^21556746 is an apocalyptic number.

21556746 is an abundant number, since it is smaller than the sum of its proper divisors (26498934).

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

21556746 is a wasteful number, since it uses less digits than its factorization.

21556746 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1275 (or 1269 counting only the distinct ones).

The product of its digits is 50400, while the sum is 36.

The square root of 21556746 is about 4642.9242940199. The cubic root of 21556746 is about 278.3093101604.

The spelling of 21556746 in words is "twenty-one million, five hundred fifty-six thousand, seven hundred forty-six".