21018120 has 64 divisors (see below), whose sum is σ = 66769920. Its totient is φ = 5274624.

The previous prime is 21018097. The next prime is 21018133. The reversal of 21018120 is 2181012.

It is a super-2 number, since 2×21018120² = 883522736668800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21018120.

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, 3112 + ... + 7191.

It is an arithmetic number, because the mean of its divisors is an integer number (1043280).

Almost surely, 2^21018120 is an apocalyptic number.

21018120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21018120 is an abundant number, since it is smaller than the sum of its proper divisors (45751800).

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

21018120 is a wasteful number, since it uses less digits than its factorization.

21018120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10334 (or 10330 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 21018120 is about 4584.5523227465. The cubic root of 21018120 is about 275.9717467403.

Adding to 21018120 its reverse (2181012), we get a palindrome (23199132).

The spelling of 21018120 in words is "twenty-one million, eighteen thousand, one hundred twenty".