18998778 has 8 divisors (see below), whose sum is σ = 37997568. Its totient is φ = 6332924.

The previous prime is 18998773. The next prime is 18998801. The reversal of 18998778 is 87789981.

It is a sphenic number, since it is the product of 3 distinct primes.

18998778 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (18998773) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1583226 + ... + 1583237.

It is an arithmetic number, because the mean of its divisors is an integer number (4749696).

Almost surely, 2^18998778 is an apocalyptic number.

18998778 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

18998778 is a wasteful number, since it uses less digits than its factorization.

18998778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3166468.

The product of its digits is 2032128, while the sum is 57.

The square root of 18998778 is about 4358.7587682734. The cubic root of 18998778 is about 266.8344440709.

The spelling of 18998778 in words is "eighteen million, nine hundred ninety-eight thousand, seven hundred seventy-eight".