18521220 has 48 divisors (see below), whose sum is σ = 52049088. Its totient is φ = 4920960.

The previous prime is 18521213. The next prime is 18521231. The reversal of 18521220 is 2212581.

It is a happy number.

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, 27690 + ... + 28350.

It is an arithmetic number, because the mean of its divisors is an integer number (1084356).

Almost surely, 2^18521220 is an apocalyptic number.

18521220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18521220 is an abundant number, since it is smaller than the sum of its proper divisors (33527868).

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

18521220 is a wasteful number, since it uses less digits than its factorization.

18521220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1140 (or 1138 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 18521220 is about 4303.6287014565. The cubic root of 18521220 is about 264.5797063728.

The spelling of 18521220 in words is "eighteen million, five hundred twenty-one thousand, two hundred twenty".