18780138 has 48 divisors (see below), whose sum is σ = 46407816. Its totient is φ = 5437440.

The previous prime is 18780137. The next prime is 18780149. The reversal of 18780138 is 83108781.

It can be written as a sum of positive squares in 4 ways, for example, as 15657849 + 3122289 = 3957^2 + 1767^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18780137) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1618 + ... + 6338.

Almost surely, 2^18780138 is an apocalyptic number.

18780138 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18780138, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23203908).

18780138 is an abundant number, since it is smaller than the sum of its proper divisors (27627678).

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

18780138 is a wasteful number, since it uses less digits than its factorization.

18780138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4759 (or 4756 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 18780138 is about 4333.6056581097. The cubic root of 18780138 is about 265.8069056732.

The spelling of 18780138 in words is "eighteen million, seven hundred eighty thousand, one hundred thirty-eight".