991649505800 has 96 divisors (see below), whose sum is σ = 2316657974400. Its totient is φ = 394758336000.

The previous prime is 991649505799. The next prime is 991649505827. The reversal of 991649505800 is 8505946199.

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, 47141285 + ... + 47162315.

It is an arithmetic number, because the mean of its divisors is an integer number (24131853900).

Almost surely, 2^991649505800 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 991649505800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1158328987200).

991649505800 is an abundant number, since it is smaller than the sum of its proper divisors (1325008468600).

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

991649505800 is a wasteful number, since it uses less digits than its factorization.

991649505800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22167 (or 22158 counting only the distinct ones).

The product of its (nonzero) digits is 3499200, while the sum is 56.

Adding to 991649505800 its sum of digits (56), we get a square (991649505856 = 995816²).

The spelling of 991649505800 in words is "nine hundred ninety-one billion, six hundred forty-nine million, five hundred five thousand, eight hundred".