21185536 has 44 divisors (see below), whose sum is σ = 44878428. Its totient is φ = 9961472.

The previous prime is 21185533. The next prime is 21185537. The reversal of 21185536 is 63558112.

It can be written as a sum of positive squares in 2 ways, for example, as 11943936 + 9241600 = 3456^2 + 3040^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21185498 and 21185507.

It is not an unprimeable number, because it can be changed into a prime (21185533) 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, 16800 + ... + 18016.

Almost surely, 2^21185536 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21185536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22439214).

21185536 is an abundant number, since it is smaller than the sum of its proper divisors (23692892).

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

21185536 is a wasteful number, since it uses less digits than its factorization.

21185536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1254 (or 1236 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The square root of 21185536 is about 4602.7748152609. The cubic root of 21185536 is about 276.7025440159.

The spelling of 21185536 in words is "twenty-one million, one hundred eighty-five thousand, five hundred thirty-six".