990799991 has 8 divisors (see below), whose sum is σ = 1000717200. Its totient is φ = 980895168.

The previous prime is 990799987. The next prime is 990800033. The reversal of 990799991 is 199997099.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 990799991 - 2² = 990799987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990799981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 323435 + ... + 326483.

It is an arithmetic number, because the mean of its divisors is an integer number (125089650).

Almost surely, 2^990799991 is an apocalyptic number.

990799991 is a deficient number, since it is larger than the sum of its proper divisors (9917209).

990799991 is a wasteful number, since it uses less digits than its factorization.

990799991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6193.

The product of its (nonzero) digits is 3720087, while the sum is 62.

The square root of 990799991 is about 31476.9755694539. The cubic root of 990799991 is about 996.9238775064.

The spelling of 990799991 in words is "nine hundred ninety million, seven hundred ninety-nine thousand, nine hundred ninety-one".