18691920840 has 32 divisors (see below), whose sum is σ = 56075762880. Its totient is φ = 4984512192.

The previous prime is 18691920827. The next prime is 18691920857. The reversal of 18691920840 is 4802919681.

It is a self number, because there is not a number n which added to its sum of digits gives 18691920840.

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, 77882884 + ... + 77883123.

It is an arithmetic number, because the mean of its divisors is an integer number (1752367590).

Almost surely, 2^18691920840 is an apocalyptic number.

18691920840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18691920840 is an abundant number, since it is smaller than the sum of its proper divisors (37383842040).

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

18691920840 is a wasteful number, since it uses less digits than its factorization.

18691920840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155766021 (or 155766017 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 48.

The spelling of 18691920840 in words is "eighteen billion, six hundred ninety-one million, nine hundred twenty thousand, eight hundred forty".