18780444640 has 48 divisors (see below), whose sum is σ = 44378651520. Its totient is φ = 7510510080.

The previous prime is 18780444637. The next prime is 18780444643. The reversal of 18780444640 is 4644408781.

It is an interprime number because it is at equal distance from previous prime (18780444637) and next prime (18780444643).

It is a super-2 number, since 2×18780444640² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18780444643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 916426 + ... + 936694.

It is an arithmetic number, because the mean of its divisors is an integer number (924555240).

Almost surely, 2^18780444640 is an apocalyptic number.

18780444640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18780444640 is an abundant number, since it is smaller than the sum of its proper divisors (25598206880).

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

18780444640 is a wasteful number, since it uses less digits than its factorization.

18780444640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26075 (or 26067 counting only the distinct ones).

The product of its (nonzero) digits is 688128, while the sum is 46.

The spelling of 18780444640 in words is "eighteen billion, seven hundred eighty million, four hundred forty-four thousand, six hundred forty".