18505220 has 24 divisors (see below), whose sum is σ = 39250008. Its totient is φ = 7328000.

The previous prime is 18505189. The next prime is 18505229. The reversal of 18505220 is 2250581.

It can be written as a sum of positive squares in 4 ways, for example, as 4726276 + 13778944 = 2174^2 + 3712^2 .

It is not an unprimeable number, because it can be changed into a prime (18505229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2561 + ... + 6600.

It is an arithmetic number, because the mean of its divisors is an integer number (1635417).

Almost surely, 2^18505220 is an apocalyptic number.

18505220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18505220 is an abundant number, since it is smaller than the sum of its proper divisors (20744788).

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

18505220 is a wasteful number, since it uses less digits than its factorization.

18505220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9271 (or 9269 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 23.

The square root of 18505220 is about 4301.7694033967. The cubic root of 18505220 is about 264.5034965822.

The spelling of 18505220 in words is "eighteen million, five hundred five thousand, two hundred twenty".