18420840 has 48 divisors (see below), whose sum is σ = 59868900. Its totient is φ = 4912128.

The previous prime is 18420817. The next prime is 18420863. The reversal of 18420840 is 4802481.

It is an interprime number because it is at equal distance from previous prime (18420817) and next prime (18420863).

It can be written as a sum of positive squares in 2 ways, for example, as 16499844 + 1920996 = 4062^2 + 1386^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25225 + ... + 25944.

Almost surely, 2^18420840 is an apocalyptic number.

18420840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18420840 is an abundant number, since it is smaller than the sum of its proper divisors (41448060).

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

18420840 is a wasteful number, since it uses less digits than its factorization.

18420840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51186 (or 51179 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 18420840 is about 4291.9506054940. The cubic root of 18420840 is about 264.1008567813.

The spelling of 18420840 in words is "eighteen million, four hundred twenty thousand, eight hundred forty".