991151475840 has 512 divisors, whose sum is σ = 3605572051200. Its totient is φ = 257170636800.

The previous prime is 991151475829. The next prime is 991151475859. The reversal of 991151475840 is 48574151199.

991151475840 is a `hidden beast` number, since 9 + 9 + 1 + 1 + 51 + 4 + 7 + 584 + 0 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 298268419 + ... + 298271741.

Almost surely, 2^991151475840 is an apocalyptic number.

991151475840 is a gapful number since it is divisible by the number (90) 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 991151475840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1802786025600).

991151475840 is an abundant number, since it is smaller than the sum of its proper divisors (2614420575360).

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

991151475840 is a wasteful number, since it uses less digits than its factorization.

991151475840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3813 (or 3795 counting only the distinct ones).

The product of its (nonzero) digits is 1814400, while the sum is 54.

The spelling of 991151475840 in words is "nine hundred ninety-one billion, one hundred fifty-one million, four hundred seventy-five thousand, eight hundred forty".