18291220 has 12 divisors (see below), whose sum is σ = 38411604. Its totient is φ = 7316480.

The previous prime is 18291179. The next prime is 18291241. The reversal of 18291220 is 2219281.

It can be written as a sum of positive squares in 2 ways, for example, as 14243076 + 4048144 = 3774^2 + 2012^2 .

It is a congruent 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, 457261 + ... + 457300.

It is an arithmetic number, because the mean of its divisors is an integer number (3200967).

Almost surely, 2^18291220 is an apocalyptic number.

18291220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18291220 is an abundant number, since it is smaller than the sum of its proper divisors (20120384).

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

18291220 is a wasteful number, since it uses less digits than its factorization.

18291220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 914570 (or 914568 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 18291220 is about 4276.8235876641. The cubic root of 18291220 is about 263.4799411510.

The spelling of 18291220 in words is "eighteen million, two hundred ninety-one thousand, two hundred twenty".