91023181 has 2 divisors, whose sum is σ = 91023182. Its totient is φ = 91023180.

The previous prime is 91023173. The next prime is 91023193. The reversal of 91023181 is 18132019.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90897156 + 126025 = 9534^2 + 355^2 .

It is an emirp because it is prime and its reverse (18132019) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91023181 - 2³ = 91023173 is a prime.

It is a super-2 number, since 2×91023181² = 16570438958717522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91021181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45511590 + 45511591.

It is an arithmetic number, because the mean of its divisors is an integer number (45511591).

Almost surely, 2^91023181 is an apocalyptic number.

It is an amenable number.

91023181 is a deficient number, since it is larger than the sum of its proper divisors (1).

91023181 is an equidigital number, since it uses as much as digits as its factorization.

91023181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 91023181 is about 9540.6069513422. The cubic root of 91023181 is about 449.8323342449.

It can be divided in two parts, 91023 and 181, that added together give a square (91204 = 302²).

The spelling of 91023181 in words is "ninety-one million, twenty-three thousand, one hundred eighty-one".