91161209 has 2 divisors, whose sum is σ = 91161210. Its totient is φ = 91161208.

The previous prime is 91161151. The next prime is 91161223. The reversal of 91161209 is 90216119.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73479184 + 17682025 = 8572^2 + 4205^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91161209 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (91161269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45580604 + 45580605.

It is an arithmetic number, because the mean of its divisors is an integer number (45580605).

Almost surely, 2^91161209 is an apocalyptic number.

It is an amenable number.

91161209 is a deficient number, since it is larger than the sum of its proper divisors (1).

91161209 is an equidigital number, since it uses as much as digits as its factorization.

91161209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 972, while the sum is 29.

The square root of 91161209 is about 9547.8379227970. The cubic root of 91161209 is about 450.0595953994.

The spelling of 91161209 in words is "ninety-one million, one hundred sixty-one thousand, two hundred nine".