18821664 has 36 divisors (see below), whose sum is σ = 53524926. Its totient is φ = 6273792.

The previous prime is 18821657. The next prime is 18821689. The reversal of 18821664 is 46612881.

It can be written as a sum of positive squares in only one way, i.e., 12531600 + 6290064 = 3540^2 + 2508^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32389 + ... + 32964.

Almost surely, 2^18821664 is an apocalyptic number.

It is an amenable number.

18821664 is an abundant number, since it is smaller than the sum of its proper divisors (34703262).

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

18821664 is a wasteful number, since it uses less digits than its factorization.

18821664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65369 (or 65358 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 18821664 is about 4338.3941729631. The cubic root of 18821664 is about 266.0026758357.

The spelling of 18821664 in words is "eighteen million, eight hundred twenty-one thousand, six hundred sixty-four".