91998993 has 8 divisors (see below), whose sum is σ = 123418528. Its totient is φ = 60956064.

The previous prime is 91998961. The next prime is 91999009. The reversal of 91998993 is 39989919.

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

It is not a de Polignac number, because 91998993 - 2⁵ = 91998961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91998913) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 93580 + ... + 94557.

It is an arithmetic number, because the mean of its divisors is an integer number (15427316).

Almost surely, 2^91998993 is an apocalyptic number.

It is an amenable number.

91998993 is a deficient number, since it is larger than the sum of its proper divisors (31419535).

91998993 is a wasteful number, since it uses less digits than its factorization.

91998993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188303.

The product of its digits is 1417176, while the sum is 57.

The square root of 91998993 is about 9591.6105529781. The cubic root of 91998993 is about 451.4340964552.

The spelling of 91998993 in words is "ninety-one million, nine hundred ninety-eight thousand, nine hundred ninety-three".