21597956 has 12 divisors (see below), whose sum is σ = 40019868. Its totient is φ = 10163712.

The previous prime is 21597949. The next prime is 21597971. The reversal of 21597956 is 65979512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 5837056 + 15760900 = 2416^2 + 3970^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 158741 + ... + 158876.

It is an arithmetic number, because the mean of its divisors is an integer number (3334989).

Almost surely, 2^21597956 is an apocalyptic number.

It is an amenable number.

21597956 is a deficient number, since it is larger than the sum of its proper divisors (18421912).

21597956 is a wasteful number, since it uses less digits than its factorization.

21597956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 317638 (or 317636 counting only the distinct ones).

The product of its digits is 170100, while the sum is 44.

The square root of 21597956 is about 4647.3601108586. The cubic root of 21597956 is about 278.4865451030.

The spelling of 21597956 in words is "twenty-one million, five hundred ninety-seven thousand, nine hundred fifty-six".