91638541 has 2 divisors, whose sum is σ = 91638542. Its totient is φ = 91638540.

The previous prime is 91638497. The next prime is 91638559. The reversal of 91638541 is 14583619.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 87497316 + 4141225 = 9354^2 + 2035^2 .

It is a cyclic number.

It is not a de Polignac number, because 91638541 - 2⁷ = 91638413 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91638541.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91638571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45819270 + 45819271.

It is an arithmetic number, because the mean of its divisors is an integer number (45819271).

Almost surely, 2^91638541 is an apocalyptic number.

It is an amenable number.

91638541 is a deficient number, since it is larger than the sum of its proper divisors (1).

91638541 is an equidigital number, since it uses as much as digits as its factorization.

91638541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 37.

The square root of 91638541 is about 9572.8021498410. The cubic root of 91638541 is about 450.8437519521.

The spelling of 91638541 in words is "ninety-one million, six hundred thirty-eight thousand, five hundred forty-one".