18666816 has 224 divisors, whose sum is σ = 64373760. Its totient is φ = 4644864.

The previous prime is 18666779. The next prime is 18666821. The reversal of 18666816 is 61866681.

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 434091 + ... + 434133.

Almost surely, 2^18666816 is an apocalyptic number.

18666816 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18666816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32186880).

18666816 is an abundant number, since it is smaller than the sum of its proper divisors (45706944).

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

18666816 is a wasteful number, since it uses less digits than its factorization.

18666816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101 (or 91 counting only the distinct ones).

The product of its digits is 82944, while the sum is 42.

The square root of 18666816 is about 4320.5110808792. The cubic root of 18666816 is about 265.2711879125.

The spelling of 18666816 in words is "eighteen million, six hundred sixty-six thousand, eight hundred sixteen".