21660036 has 12 divisors (see below), whose sum is σ = 50540112. Its totient is φ = 7220008.

The previous prime is 21660011. The next prime is 21660047. The reversal of 21660036 is 63006612.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (24) 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 = 21659988 and 21660015.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 902490 + ... + 902513.

It is an arithmetic number, because the mean of its divisors is an integer number (4211676).

Almost surely, 2^21660036 is an apocalyptic number.

It is an amenable number.

21660036 is an abundant number, since it is smaller than the sum of its proper divisors (28880076).

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

21660036 is a wasteful number, since it uses less digits than its factorization.

21660036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1805010 (or 1805008 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 24.

The square root of 21660036 is about 4654.0343789018. The cubic root of 21660036 is about 278.7531120997.

Adding to 21660036 its reverse (63006612), we get a palindrome (84666648).

The spelling of 21660036 in words is "twenty-one million, six hundred sixty thousand, thirty-six".