91999660 has 12 divisors (see below), whose sum is σ = 193199328. Its totient is φ = 36799856.

The previous prime is 91999627. The next prime is 91999693. The reversal of 91999660 is 6699919.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (91999627) and next prime (91999693).

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2299972 + ... + 2300011.

It is an arithmetic number, because the mean of its divisors is an integer number (16099944).

Almost surely, 2^91999660 is an apocalyptic number.

It is an amenable number.

91999660 is an abundant number, since it is smaller than the sum of its proper divisors (101199668).

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

91999660 is a wasteful number, since it uses less digits than its factorization.

91999660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4599992 (or 4599990 counting only the distinct ones).

The product of its (nonzero) digits is 236196, while the sum is 49.

The square root of 91999660 is about 9591.6453228839. The cubic root of 91999660 is about 451.4351874302.

The spelling of 91999660 in words is "ninety-one million, nine hundred ninety-nine thousand, six hundred sixty".