991455788624 has 80 divisors (see below), whose sum is σ = 2231921731200. Its totient is φ = 417837934080.

The previous prime is 991455788593. The next prime is 991455788657. The reversal of 991455788624 is 426887554199.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30680027 + ... + 30712325.

It is an arithmetic number, because the mean of its divisors is an integer number (27899021640).

Almost surely, 2^991455788624 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 991455788624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1115960865600).

991455788624 is an abundant number, since it is smaller than the sum of its proper divisors (1240465942576).

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

991455788624 is a wasteful number, since it uses less digits than its factorization.

991455788624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36868 (or 36862 counting only the distinct ones).

The product of its digits is 174182400, while the sum is 68.

The spelling of 991455788624 in words is "nine hundred ninety-one billion, four hundred fifty-five million, seven hundred eighty-eight thousand, six hundred twenty-four".