18915978336 has 96 divisors (see below), whose sum is σ = 52776396288. Its totient is φ = 5911726080.

The previous prime is 18915978331. The next prime is 18915978337. The reversal of 18915978336 is 63387951981.

It is a tau number, because it is divible by the number of its divisors (96).

It is a self number, because there is not a number n which added to its sum of digits gives 18915978336.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18915978331) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 407181 + ... + 451251.

It is an arithmetic number, because the mean of its divisors is an integer number (549754128).

Almost surely, 2^18915978336 is an apocalyptic number.

18915978336 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18915978336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26388198144).

18915978336 is an abundant number, since it is smaller than the sum of its proper divisors (33860417952).

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

18915978336 is a wasteful number, since it uses less digits than its factorization.

18915978336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44364 (or 44356 counting only the distinct ones).

The product of its digits is 9797760, while the sum is 60.

The spelling of 18915978336 in words is "eighteen billion, nine hundred fifteen million, nine hundred seventy-eight thousand, three hundred thirty-six".