91651993 has 2 divisors, whose sum is σ = 91651994. Its totient is φ = 91651992.

The previous prime is 91651979. The next prime is 91652023. The reversal of 91651993 is 39915619.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80946009 + 10705984 = 8997^2 + 3272^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91651993 is a prime.

It is not a weakly prime, because it can be changed into another prime (91651943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45825996 + 45825997.

It is an arithmetic number, because the mean of its divisors is an integer number (45825997).

Almost surely, 2^91651993 is an apocalyptic number.

It is an amenable number.

91651993 is a deficient number, since it is larger than the sum of its proper divisors (1).

91651993 is an equidigital number, since it uses as much as digits as its factorization.

91651993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 65610, while the sum is 43.

The square root of 91651993 is about 9573.5047396447. The cubic root of 91651993 is about 450.8658112783.

The spelling of 91651993 in words is "ninety-one million, six hundred fifty-one thousand, nine hundred ninety-three".