18402978 has 32 divisors (see below), whose sum is σ = 40917312. Its totient is φ = 5470400.

The previous prime is 18402961. The next prime is 18402983. The reversal of 18402978 is 87920481.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 868 + ... + 6128.

It is an arithmetic number, because the mean of its divisors is an integer number (1278666).

Almost surely, 2^18402978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18402978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20458656).

18402978 is an abundant number, since it is smaller than the sum of its proper divisors (22514334).

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

18402978 is a wasteful number, since it uses less digits than its factorization.

18402978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5330.

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 18402978 is about 4289.8692287761. The cubic root of 18402978 is about 264.0154662656.

The spelling of 18402978 in words is "eighteen million, four hundred two thousand, nine hundred seventy-eight".