91997 has 2 divisors, whose sum is σ = 91998. Its totient is φ = 91996.

The previous prime is 91969. The next prime is 92003. The reversal of 91997 is 79919.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81796 + 10201 = 286^2 + 101^2 .

91997 is a truncatable prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91997 is a prime.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 91997.

It is not a weakly prime, because it can be changed into another prime (91957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45998 + 45999.

It is an arithmetic number, because the mean of its divisors is an integer number (45999).

2⁹¹⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

91997 is a deficient number, since it is larger than the sum of its proper divisors (1).

91997 is an equidigital number, since it uses as much as digits as its factorization.

91997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5103, while the sum is 35.

The square root of 91997 is about 303.3100723682. The cubic root of 91997 is about 45.1430836584.

The spelling of 91997 in words is "ninety-one thousand, nine hundred ninety-seven".