18643983920 has 40 divisors (see below), whose sum is σ = 43941074496. Its totient is φ = 7355432448.

The previous prime is 18643983901. The next prime is 18643983937. The reversal of 18643983920 is 2938934681.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1590392 + ... + 1602071.

Almost surely, 2^18643983920 is an apocalyptic number.

18643983920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18643983920 is an abundant number, since it is smaller than the sum of its proper divisors (25297090576).

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

18643983920 is a wasteful number, since it uses less digits than its factorization.

18643983920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3192549 (or 3192543 counting only the distinct ones).

The product of its (nonzero) digits is 2239488, while the sum is 53.

The spelling of 18643983920 in words is "eighteen billion, six hundred forty-three million, nine hundred eighty-three thousand, nine hundred twenty".