21636516 has 48 divisors (see below), whose sum is σ = 57980160. Its totient is φ = 6210720.

The previous prime is 21636499. The next prime is 21636521. The reversal of 21636516 is 61563612.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1806 + ... + 6821.

It is an arithmetic number, because the mean of its divisors is an integer number (1207920).

Almost surely, 2^21636516 is an apocalyptic number.

It is an amenable number.

21636516 is an abundant number, since it is smaller than the sum of its proper divisors (36343644).

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

21636516 is a wasteful number, since it uses less digits than its factorization.

21636516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8664 (or 8662 counting only the distinct ones).

The product of its digits is 6480, while the sum is 30.

The square root of 21636516 is about 4651.5068526231. The cubic root of 21636516 is about 278.6521789385.

The spelling of 21636516 in words is "twenty-one million, six hundred thirty-six thousand, five hundred sixteen".