21180812 has 12 divisors (see below), whose sum is σ = 38262336. Its totient is φ = 10248720.

The previous prime is 21180799. The next prime is 21180857. The reversal of 21180812 is 21808112.

It is a happy number.

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, 85283 + ... + 85530.

It is an arithmetic number, because the mean of its divisors is an integer number (3188528).

Almost surely, 2^21180812 is an apocalyptic number.

It is an amenable number.

21180812 is a deficient number, since it is larger than the sum of its proper divisors (17081524).

21180812 is a wasteful number, since it uses less digits than its factorization.

21180812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170848 (or 170846 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 23.

The square root of 21180812 is about 4602.2616179439. The cubic root of 21180812 is about 276.6819758952.

Adding to 21180812 its reverse (21808112), we get a palindrome (42988924).

The spelling of 21180812 in words is "twenty-one million, one hundred eighty thousand, eight hundred twelve".