18381820 has 24 divisors (see below), whose sum is σ = 38685024. Its totient is φ = 7336896.

The previous prime is 18381787. The next prime is 18381821. The reversal of 18381820 is 2818381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18381821) 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, 14242 + ... + 15478.

It is an arithmetic number, because the mean of its divisors is an integer number (1611876).

Almost surely, 2^18381820 is an apocalyptic number.

18381820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18381820 is an abundant number, since it is smaller than the sum of its proper divisors (20303204).

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

18381820 is a wasteful number, since it uses less digits than its factorization.

18381820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1989 (or 1987 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 18381820 is about 4287.4024770250. The cubic root of 18381820 is about 263.9142474779.

The spelling of 18381820 in words is "eighteen million, three hundred eighty-one thousand, eight hundred twenty".