91331813 has 2 divisors, whose sum is σ = 91331814. Its totient is φ = 91331812.

The previous prime is 91331809. The next prime is 91331819. The reversal of 91331813 is 31813319.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80586529 + 10745284 = 8977^2 + 3278^2 .

It is a cyclic number.

It is not a de Polignac number, because 91331813 - 2² = 91331809 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91331819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45665906 + 45665907.

It is an arithmetic number, because the mean of its divisors is an integer number (45665907).

Almost surely, 2^91331813 is an apocalyptic number.

It is an amenable number.

91331813 is a deficient number, since it is larger than the sum of its proper divisors (1).

91331813 is an equidigital number, since it uses as much as digits as its factorization.

91331813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 29.

The square root of 91331813 is about 9556.7679159850. The cubic root of 91331813 is about 450.3401757025.

The spelling of 91331813 in words is "ninety-one million, three hundred thirty-one thousand, eight hundred thirteen".