18778864 has 40 divisors (see below), whose sum is σ = 39528720. Its totient is φ = 8590848.

The previous prime is 18778849. The next prime is 18778871. The reversal of 18778864 is 46887781.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28167 + ... + 28825.

It is an arithmetic number, because the mean of its divisors is an integer number (988218).

Almost surely, 2^18778864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18778864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19764360).

18778864 is an abundant number, since it is smaller than the sum of its proper divisors (20749856).

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

18778864 is a wasteful number, since it uses less digits than its factorization.

18778864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817 (or 811 counting only the distinct ones).

The product of its digits is 602112, while the sum is 49.

The square root of 18778864 is about 4333.4586648542. The cubic root of 18778864 is about 265.8008949673.

The spelling of 18778864 in words is "eighteen million, seven hundred seventy-eight thousand, eight hundred sixty-four".