91421581 has 2 divisors, whose sum is σ = 91421582. Its totient is φ = 91421580.

The previous prime is 91421537. The next prime is 91421587. The reversal of 91421581 is 18512419.

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., 58828900 + 32592681 = 7670^2 + 5709^2 .

It is an emirp because it is prime and its reverse (18512419) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91421581 - 2⁷ = 91421453 is a prime.

It is a super-2 number, since 2×91421581² = 16715810945079122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91421587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45710790 + 45710791.

It is an arithmetic number, because the mean of its divisors is an integer number (45710791).

Almost surely, 2^91421581 is an apocalyptic number.

It is an amenable number.

91421581 is a deficient number, since it is larger than the sum of its proper divisors (1).

91421581 is an equidigital number, since it uses as much as digits as its factorization.

91421581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 31.

The square root of 91421581 is about 9561.4633294282. The cubic root of 91421581 is about 450.4876704916.

The spelling of 91421581 in words is "ninety-one million, four hundred twenty-one thousand, five hundred eighty-one".