18231220 has 24 divisors (see below), whose sum is σ = 43755264. Its totient is φ = 6250656.

The previous prime is 18231217. The next prime is 18231221. The reversal of 18231220 is 2213281.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18231221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64972 + ... + 65251.

It is an arithmetic number, because the mean of its divisors is an integer number (1823136).

Almost surely, 2^18231220 is an apocalyptic number.

18231220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18231220 is an abundant number, since it is smaller than the sum of its proper divisors (25524044).

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

18231220 is a wasteful number, since it uses less digits than its factorization.

18231220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130239 (or 130237 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 18231220 is about 4269.8032741568. The cubic root of 18231220 is about 263.1915311250.

The spelling of 18231220 in words is "eighteen million, two hundred thirty-one thousand, two hundred twenty".