18939564 has 72 divisors (see below), whose sum is σ = 57945888. Its totient is φ = 5091840.

The previous prime is 18939553. The next prime is 18939577. The reversal of 18939564 is 46593981.

It is a happy number.

18939564 is a `hidden beast` number, since 1 + 89 + 3 + 9 + 564 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2074 + ... + 6494.

It is an arithmetic number, because the mean of its divisors is an integer number (804804).

Almost surely, 2^18939564 is an apocalyptic number.

18939564 is a gapful number since it is divisible by the number (14) 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 18939564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28972944).

18939564 is an abundant number, since it is smaller than the sum of its proper divisors (39006324).

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

18939564 is a wasteful number, since it uses less digits than its factorization.

18939564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4455 (or 4450 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 18939564 is about 4351.9609373247. The cubic root of 18939564 is about 266.5569388833.

It can be divided in two parts, 18939 and 564, that added together give a triangular number (19503 = T₁₉₇).

The spelling of 18939564 in words is "eighteen million, nine hundred thirty-nine thousand, five hundred sixty-four".