91879999 has 2 divisors, whose sum is σ = 91880000. Its totient is φ = 91879998.

The previous prime is 91879993. The next prime is 91880021. The reversal of 91879999 is 99997819.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91879999 - 2⁵ = 91879967 is a prime.

91879999 is a modest number, since divided by 9999 gives 9187 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91879993) by changing a digit.

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 as a sum of consecutive naturals, namely, 45939999 + 45940000.

It is an arithmetic number, because the mean of its divisors is an integer number (45940000).

Almost surely, 2^91879999 is an apocalyptic number.

91879999 is a deficient number, since it is larger than the sum of its proper divisors (1).

91879999 is an equidigital number, since it uses as much as digits as its factorization.

91879999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3306744, while the sum is 61.

The square root of 91879999 is about 9585.4055208948. The cubic root of 91879999 is about 451.2393801006.

The spelling of 91879999 in words is "ninety-one million, eight hundred seventy-nine thousand, nine hundred ninety-nine".