18915509440 has 28 divisors (see below), whose sum is σ = 45042557616. Its totient is φ = 7566203648.

The previous prime is 18915509383. The next prime is 18915509441. The reversal of 18915509440 is 4490551981.

It is a happy number.

It is a super-2 number, since 2×18915509440² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18915509441) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29555164 + ... + 29555803.

It is an arithmetic number, because the mean of its divisors is an integer number (1608662772).

Almost surely, 2^18915509440 is an apocalyptic number.

18915509440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18915509440 is an abundant number, since it is smaller than the sum of its proper divisors (26127048176).

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

18915509440 is an equidigital number, since it uses as much as digits as its factorization.

18915509440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59110984 (or 59110974 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 46.

The spelling of 18915509440 in words is "eighteen billion, nine hundred fifteen million, five hundred nine thousand, four hundred forty".