21653536 has 24 divisors (see below), whose sum is σ = 43333164. Its totient is φ = 10648320.

The previous prime is 21653507. The next prime is 21653537. The reversal of 21653536 is 63535612.

It can be written as a sum of positive squares in 2 ways, for example, as 21344400 + 309136 = 4620^2 + 556^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21653498 and 21653507.

It is not an unprimeable number, because it can be changed into a prime (21653537) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3595 + ... + 7498.

Almost surely, 2^21653536 is an apocalyptic number.

It is an amenable number.

21653536 is an abundant number, since it is smaller than the sum of its proper divisors (21679628).

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

21653536 is a wasteful number, since it uses less digits than its factorization.

21653536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11164 (or 11156 counting only the distinct ones).

The product of its digits is 16200, while the sum is 31.

The square root of 21653536 is about 4653.3360076401. The cubic root of 21653536 is about 278.7252254655.

The spelling of 21653536 in words is "twenty-one million, six hundred fifty-three thousand, five hundred thirty-six".