991609008390 has 2048 divisors, whose sum is σ = 4077261619200. Its totient is φ = 164467998720.

The previous prime is 991609008389. The next prime is 991609008437. The reversal of 991609008390 is 93800906199.

991609008390 is a `hidden beast` number, since 9 + 9 + 160 + 90 + 0 + 8 + 390 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 1023 ways as a sum of consecutive naturals, for example, 3229996617 + ... + 3229996923.

It is an arithmetic number, because the mean of its divisors is an integer number (1990850400).

Almost surely, 2^991609008390 is an apocalyptic number.

991609008390 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 991609008390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2038630809600).

991609008390 is an abundant number, since it is smaller than the sum of its proper divisors (3085652610810).

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

991609008390 is a wasteful number, since it uses less digits than its factorization.

991609008390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 427 (or 421 counting only the distinct ones).

The product of its (nonzero) digits is 944784, while the sum is 54.

The spelling of 991609008390 in words is "nine hundred ninety-one billion, six hundred nine million, eight thousand, three hundred ninety".