991386320490 has 80 divisors (see below), whose sum is σ = 2666120161320. Its totient is φ = 264330760320.

The previous prime is 991386320489. The next prime is 991386320503. The reversal of 991386320490 is 94023683199.

991386320490 is a `hidden beast` number, since 9 + 91 + 3 + 8 + 63 + 2 + 0 + 490 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 894062911401 + 97323409089 = 945549^2 + 311967^2 .

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 39 ways as a sum of consecutive naturals, for example, 5639320 + ... + 5812460.

Almost surely, 2^991386320490 is an apocalyptic number.

991386320490 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

991386320490 is an abundant number, since it is smaller than the sum of its proper divisors (1674733840830).

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

991386320490 is a wasteful number, since it uses less digits than its factorization.

991386320490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180229 (or 180220 counting only the distinct ones).

The product of its (nonzero) digits is 2519424, while the sum is 54.

The spelling of 991386320490 in words is "nine hundred ninety-one billion, three hundred eighty-six million, three hundred twenty thousand, four hundred ninety".