91891073 has 2 divisors, whose sum is σ = 91891074. Its totient is φ = 91891072.

The previous prime is 91891067. The next prime is 91891081. The reversal of 91891073 is 37019819.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 83028544 + 8862529 = 9112^2 + 2977^2 .

It is an emirp because it is prime and its reverse (37019819) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91891073 - 2⁴ = 91891057 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (91891573) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45945536 + 45945537.

It is an arithmetic number, because the mean of its divisors is an integer number (45945537).

Almost surely, 2^91891073 is an apocalyptic number.

It is an amenable number.

91891073 is a deficient number, since it is larger than the sum of its proper divisors (1).

91891073 is an equidigital number, since it uses as much as digits as its factorization.

91891073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13608, while the sum is 38.

The square root of 91891073 is about 9585.9831524993. The cubic root of 91891073 is about 451.2575081815.

The spelling of 91891073 in words is "ninety-one million, eight hundred ninety-one thousand, seventy-three".