18891816 has 64 divisors (see below), whose sum is σ = 49230720. Its totient is φ = 6036480.

The previous prime is 18891787. The next prime is 18891827. The reversal of 18891816 is 61819881.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71701 + ... + 71963.

It is an arithmetic number, because the mean of its divisors is an integer number (769230).

Almost surely, 2^18891816 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 18891816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24615360).

18891816 is an abundant number, since it is smaller than the sum of its proper divisors (30338904).

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

18891816 is a wasteful number, since it uses less digits than its factorization.

18891816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386 (or 382 counting only the distinct ones).

The product of its digits is 27648, while the sum is 42.

The square root of 18891816 is about 4346.4716725178. The cubic root of 18891816 is about 266.3327473193.

The spelling of 18891816 in words is "eighteen million, eight hundred ninety-one thousand, eight hundred sixteen".