18977816 has 64 divisors (see below), whose sum is σ = 42729120. Its totient is φ = 7787520.

The previous prime is 18977813. The next prime is 18977843. The reversal of 18977816 is 61877981.

Its product of digits (169344) is a multiple of the sum of its prime divisors (392).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18977813) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60476 + ... + 60788.

Almost surely, 2^18977816 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 18977816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21364560).

18977816 is an abundant number, since it is smaller than the sum of its proper divisors (23751304).

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

18977816 is a wasteful number, since it uses less digits than its factorization.

18977816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 396 (or 392 counting only the distinct ones).

The product of its digits is 169344, while the sum is 47.

The square root of 18977816 is about 4356.3535210081. The cubic root of 18977816 is about 266.7362721078.

The spelling of 18977816 in words is "eighteen million, nine hundred seventy-seven thousand, eight hundred sixteen".