18981312 has 112 divisors (see below), whose sum is σ = 59496960. Its totient is φ = 5225472.

The previous prime is 18981307. The next prime is 18981329. The reversal of 18981312 is 21318981.

It is a tau number, because it is divible by the number of its divisors (112).

It is a congruent number.

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, 38733 + ... + 39219.

Almost surely, 2^18981312 is an apocalyptic number.

18981312 is a gapful number since it is divisible by the number (12) 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 18981312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29748480).

18981312 is an abundant number, since it is smaller than the sum of its proper divisors (40515648).

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

18981312 is a wasteful number, since it uses less digits than its factorization.

18981312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 538 (or 528 counting only the distinct ones).

The product of its digits is 3456, while the sum is 33.

The square root of 18981312 is about 4356.7547555491. The cubic root of 18981312 is about 266.7526500505.

The spelling of 18981312 in words is "eighteen million, nine hundred eighty-one thousand, three hundred twelve".