991596838464 has 224 divisors, whose sum is σ = 3091847552640. Its totient is φ = 310559145984.

The previous prime is 991596838457. The next prime is 991596838469. The reversal of 991596838464 is 464838695199.

991596838464 is a `hidden beast` number, since 9 + 9 + 159 + 6 + 8 + 3 + 8 + 464 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 991596838392 and 991596838401.

It is not an unprimeable number, because it can be changed into a prime (991596838469) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17391507 + ... + 17448429.

It is an arithmetic number, because the mean of its divisors is an integer number (13802890860).

Almost surely, 2^991596838464 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991596838464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1545923776320).

991596838464 is an abundant number, since it is smaller than the sum of its proper divisors (2100250714176).

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

991596838464 is a wasteful number, since it uses less digits than its factorization.

991596838464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57554 (or 57538 counting only the distinct ones).

The product of its digits is 403107840, while the sum is 72.

The spelling of 991596838464 in words is "nine hundred ninety-one billion, five hundred ninety-six million, eight hundred thirty-eight thousand, four hundred sixty-four".