999991166580 has 288 divisors, whose sum is σ = 3653845977600. Its totient is φ = 216523367424.

The previous prime is 999991166543. The next prime is 999991166597. The reversal of 999991166580 is 85661199999.

It is a junction number, because it is equal to n+sod(n) for n = 999991166499 and 999991166508.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1678441 + ... + 2194799.

It is an arithmetic number, because the mean of its divisors is an integer number (12686965200).

Almost surely, 2^999991166580 is an apocalyptic number.

999991166580 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 999991166580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1826922988800).

999991166580 is an abundant number, since it is smaller than the sum of its proper divisors (2653854811020).

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

999991166580 is a wasteful number, since it uses less digits than its factorization.

999991166580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 516463 (or 516458 counting only the distinct ones).

The product of its (nonzero) digits is 85030560, while the sum is 72.

The spelling of 999991166580 in words is "nine hundred ninety-nine billion, nine hundred ninety-one million, one hundred sixty-six thousand, five hundred eighty".