18211980 has 48 divisors (see below), whose sum is σ = 51184224. Its totient is φ = 4838400.

The previous prime is 18211969. The next prime is 18211987. The reversal of 18211980 is 8911281.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (18211987) 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 15 ways as a sum of consecutive naturals, for example, 25630 + ... + 26330.

It is an arithmetic number, because the mean of its divisors is an integer number (1066338).

Almost surely, 2^18211980 is an apocalyptic number.

18211980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18211980 is an abundant number, since it is smaller than the sum of its proper divisors (32972244).

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

18211980 is a wasteful number, since it uses less digits than its factorization.

18211980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1146 (or 1144 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 30.

The square root of 18211980 is about 4267.5496482173. The cubic root of 18211980 is about 263.0989136729.

It can be divided in two parts, 18211 and 980, that added together give a palindrome (19191).

The spelling of 18211980 in words is "eighteen million, two hundred eleven thousand, nine hundred eighty".