991637136 has 120 divisors (see below), whose sum is σ = 3281129280. Its totient is φ = 273547008.

The previous prime is 991637123. The next prime is 991637197. The reversal of 991637136 is 631736199.

991637136 is a `hidden beast` number, since 9 + 9 + 1 + 637 + 1 + 3 + 6 = 666.

991637136 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 991637091 and 991637100.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12271 + ... + 46193.

It is an arithmetic number, because the mean of its divisors is an integer number (27342744).

Almost surely, 2^991637136 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 991637136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1640564640).

991637136 is an abundant number, since it is smaller than the sum of its proper divisors (2289492144).

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

991637136 is a wasteful number, since it uses less digits than its factorization.

991637136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33973 (or 33964 counting only the distinct ones).

The product of its digits is 183708, while the sum is 45.

The square root of 991637136 is about 31490.2704974092. The cubic root of 991637136 is about 997.2045715279.

The spelling of 991637136 in words is "nine hundred ninety-one million, six hundred thirty-seven thousand, one hundred thirty-six".