91638413 has 2 divisors, whose sum is σ = 91638414. Its totient is φ = 91638412.

The previous prime is 91638383. The next prime is 91638451. The reversal of 91638413 is 31483619.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80335369 + 11303044 = 8963^2 + 3362^2 .

It is a cyclic number.

It is not a de Polignac number, because 91638413 - 2¹² = 91634317 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91638473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45819206 + 45819207.

It is an arithmetic number, because the mean of its divisors is an integer number (45819207).

Almost surely, 2^91638413 is an apocalyptic number.

It is an amenable number.

91638413 is a deficient number, since it is larger than the sum of its proper divisors (1).

91638413 is an equidigital number, since it uses as much as digits as its factorization.

91638413 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 35.

The square root of 91638413 is about 9572.7954642309. The cubic root of 91638413 is about 450.8435420403.

It can be divided in two parts, 9163 and 8413, that added together give a cube (17576 = 26³).

The spelling of 91638413 in words is "ninety-one million, six hundred thirty-eight thousand, four hundred thirteen".