91817251 has 2 divisors, whose sum is σ = 91817252. Its totient is φ = 91817250.

The previous prime is 91817249. The next prime is 91817303. The reversal of 91817251 is 15271819.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91817251 - 2¹ = 91817249 is a prime.

Together with 91817249, it forms a pair of twin primes.

It is equal to p_5316289 and since 91817251 and 5316289 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (91817851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45908625 + 45908626.

It is an arithmetic number, because the mean of its divisors is an integer number (45908626).

Almost surely, 2^91817251 is an apocalyptic number.

91817251 is a deficient number, since it is larger than the sum of its proper divisors (1).

91817251 is an equidigital number, since it uses as much as digits as its factorization.

91817251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 34.

The square root of 91817251 is about 9582.1318609170. The cubic root of 91817251 is about 451.1366344288.

The spelling of 91817251 in words is "ninety-one million, eight hundred seventeen thousand, two hundred fifty-one".