91189979 has 2 divisors, whose sum is σ = 91189980. Its totient is φ = 91189978.

The previous prime is 91189933. The next prime is 91189981. The reversal of 91189979 is 97998119.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91189979 - 2⁸ = 91189723 is a prime.

It is a super-2 number, since 2×91189979² = 16631224540040882, which contains 22 as substring.

Together with 91189981, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91189979.

It is not a weakly prime, because it can be changed into another prime (91183979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45594989 + 45594990.

It is an arithmetic number, because the mean of its divisors is an integer number (45594990).

Almost surely, 2^91189979 is an apocalyptic number.

91189979 is a deficient number, since it is larger than the sum of its proper divisors (1).

91189979 is an equidigital number, since it uses as much as digits as its factorization.

91189979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 367416, while the sum is 53.

The square root of 91189979 is about 9549.3444277605. The cubic root of 91189979 is about 450.1069359031.

The spelling of 91189979 in words is "ninety-one million, one hundred eighty-nine thousand, nine hundred seventy-nine".