991741121280 has 1728 divisors, whose sum is σ = 4642797196800. Its totient is φ = 198149898240.

The previous prime is 991741121269. The next prime is 991741121303. The reversal of 991741121280 is 82121147199.

991741121280 is a `hidden beast` number, since 9 + 9 + 17 + 411 + 212 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1728).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 418278495 + ... + 418280865.

Almost surely, 2^991741121280 is an apocalyptic number.

991741121280 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 991741121280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2321398598400).

991741121280 is an abundant number, since it is smaller than the sum of its proper divisors (3651056075520).

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

991741121280 is a wasteful number, since it uses less digits than its factorization.

991741121280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2447 (or 2420 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 45.

The spelling of 991741121280 in words is "nine hundred ninety-one billion, seven hundred forty-one million, one hundred twenty-one thousand, two hundred eighty".