91913881 has 2 divisors, whose sum is σ = 91913882. Its totient is φ = 91913880.

The previous prime is 91913879. The next prime is 91913891. The reversal of 91913881 is 18831919.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77352025 + 14561856 = 8795^2 + 3816^2 .

It is a cyclic number.

It is not a de Polignac number, because 91913881 - 2¹ = 91913879 is a prime.

It is a super-2 number, since 2×91913881² = 16896323040964322, which contains 22 as substring.

Together with 91913879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (91913821) 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 as a sum of consecutive naturals, namely, 45956940 + 45956941.

It is an arithmetic number, because the mean of its divisors is an integer number (45956941).

Almost surely, 2^91913881 is an apocalyptic number.

It is an amenable number.

91913881 is a deficient number, since it is larger than the sum of its proper divisors (1).

91913881 is an equidigital number, since it uses as much as digits as its factorization.

91913881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 40.

The square root of 91913881 is about 9587.1727323544. The cubic root of 91913881 is about 451.2948401714.

The spelling of 91913881 in words is "ninety-one million, nine hundred thirteen thousand, eight hundred eighty-one".