18122778 has 20 divisors (see below), whose sum is σ = 40608810. Its totient is φ = 6040872.

The previous prime is 18122759. The next prime is 18122791. The reversal of 18122778 is 87722181.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18122049 + 729 = 4257^2 + 27^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 55773 + ... + 56096.

Almost surely, 2^18122778 is an apocalyptic number.

18122778 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

18122778 is an abundant number, since it is smaller than the sum of its proper divisors (22486032).

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

18122778 is a wasteful number, since it uses less digits than its factorization.

18122778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111883 (or 111874 counting only the distinct ones).

The product of its digits is 12544, while the sum is 36.

The square root of 18122778 is about 4257.0856228176. The cubic root of 18122778 is about 262.6686589586.

The spelling of 18122778 in words is "eighteen million, one hundred twenty-two thousand, seven hundred seventy-eight".