18861984 has 120 divisors (see below), whose sum is σ = 58544640. Its totient is φ = 5940864.

The previous prime is 18861967. The next prime is 18861989. The reversal of 18861984 is 48916881.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18861989) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 49057 + ... + 49439.

It is an arithmetic number, because the mean of its divisors is an integer number (487872).

Almost surely, 2^18861984 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 18861984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29272320).

18861984 is an abundant number, since it is smaller than the sum of its proper divisors (39682656).

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

18861984 is a wasteful number, since it uses less digits than its factorization.

18861984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 424 (or 407 counting only the distinct ones).

The product of its digits is 110592, while the sum is 45.

The square root of 18861984 is about 4343.0385676390. The cubic root of 18861984 is about 266.1924850969.

The spelling of 18861984 in words is "eighteen million, eight hundred sixty-one thousand, nine hundred eighty-four".