991613435904 has 2160 divisors, whose sum is σ = 4111731082368. Its totient is φ = 235438866432.

The previous prime is 991613435899. The next prime is 991613435971. The reversal of 991613435904 is 409534316199.

It is a happy number.

991613435904 is a `hidden beast` number, since 9 + 9 + 1 + 6 + 1 + 3 + 43 + 590 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 43113627637 + ... + 43113627659.

Almost surely, 2^991613435904 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 991613435904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2055865541184).

991613435904 is an abundant number, since it is smaller than the sum of its proper divisors (3120117646464).

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

991613435904 is a wasteful number, since it uses less digits than its factorization.

991613435904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110 (or 65 counting only the distinct ones).

The product of its (nonzero) digits is 3149280, while the sum is 54.

The spelling of 991613435904 in words is "nine hundred ninety-one billion, six hundred thirteen million, four hundred thirty-five thousand, nine hundred four".