91981249 has 2 divisors, whose sum is σ = 91981250. Its totient is φ = 91981248.

The previous prime is 91981231. The next prime is 91981283. The reversal of 91981249 is 94218919.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90916225 + 1065024 = 9535^2 + 1032^2 .

It is an emirp because it is prime and its reverse (94218919) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91981249 - 2⁵ = 91981217 is a prime.

It is not a weakly prime, because it can be changed into another prime (91981949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45990624 + 45990625.

It is an arithmetic number, because the mean of its divisors is an integer number (45990625).

Almost surely, 2^91981249 is an apocalyptic number.

It is an amenable number.

91981249 is a deficient number, since it is larger than the sum of its proper divisors (1).

91981249 is an equidigital number, since it uses as much as digits as its factorization.

91981249 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46656, while the sum is 43.

The square root of 91981249 is about 9590.6855333704. The cubic root of 91981249 is about 451.4050716388.

Subtracting 91981249 from its reverse (94218919), we obtain a triangular number (2237670 = T₂₁₁₅).

The spelling of 91981249 in words is "ninety-one million, nine hundred eighty-one thousand, two hundred forty-nine".