21506536 has 32 divisors (see below), whose sum is σ = 41738400. Its totient is φ = 10382400.

The previous prime is 21506533. The next prime is 21506593. The reversal of 21506536 is 63560512.

It is not an unprimeable number, because it can be changed into a prime (21506533) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34435 + ... + 35053.

It is an arithmetic number, because the mean of its divisors is an integer number (1304325).

Almost surely, 2^21506536 is an apocalyptic number.

It is an amenable number.

21506536 is a deficient number, since it is larger than the sum of its proper divisors (20231864).

21506536 is a wasteful number, since it uses less digits than its factorization.

21506536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769 (or 765 counting only the distinct ones).

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 21506536 is about 4637.5139891972. The cubic root of 21506536 is about 278.0930627133.

The spelling of 21506536 in words is "twenty-one million, five hundred six thousand, five hundred thirty-six".