91668517 has 2 divisors, whose sum is σ = 91668518. Its totient is φ = 91668516.

The previous prime is 91668469. The next prime is 91668523. The reversal of 91668517 is 71586619.

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., 88849476 + 2819041 = 9426^2 + 1679^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91668517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91668557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45834258 + 45834259.

It is an arithmetic number, because the mean of its divisors is an integer number (45834259).

Almost surely, 2^91668517 is an apocalyptic number.

It is an amenable number.

91668517 is a deficient number, since it is larger than the sum of its proper divisors (1).

91668517 is an equidigital number, since it uses as much as digits as its factorization.

91668517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 43.

The square root of 91668517 is about 9574.3677075826. The cubic root of 91668517 is about 450.8929052845.

The spelling of 91668517 in words is "ninety-one million, six hundred sixty-eight thousand, five hundred seventeen".