21318860 has 24 divisors (see below), whose sum is σ = 44965536. Its totient is φ = 8490240.

The previous prime is 21318859. The next prime is 21318863. The reversal of 21318860 is 6881312.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21318863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2609 + ... + 7031.

It is an arithmetic number, because the mean of its divisors is an integer number (1873564).

Almost surely, 2^21318860 is an apocalyptic number.

21318860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21318860 is an abundant number, since it is smaller than the sum of its proper divisors (23646676).

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

21318860 is a wasteful number, since it uses less digits than its factorization.

21318860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4673 (or 4671 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21318860 is about 4617.2351033925. The cubic root of 21318860 is about 277.2817752457.

The spelling of 21318860 in words is "twenty-one million, three hundred eighteen thousand, eight hundred sixty".