21637130 has 16 divisors (see below), whose sum is σ = 39030984. Its totient is φ = 8636160.

The previous prime is 21637123. The next prime is 21637151. The reversal of 21637130 is 3173612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 8116801 + 13520329 = 2849^2 + 3677^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21637096 and 21637105.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3134 + ... + 7286.

Almost surely, 2^21637130 is an apocalyptic number.

21637130 is a deficient number, since it is larger than the sum of its proper divisors (17393854).

21637130 is a wasteful number, since it uses less digits than its factorization.

21637130 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4681.

The product of its (nonzero) digits is 756, while the sum is 23.

The square root of 21637130 is about 4651.5728522727. The cubic root of 21637130 is about 278.6548147729.

The spelling of 21637130 in words is "twenty-one million, six hundred thirty-seven thousand, one hundred thirty".