91813 has 2 divisors, whose sum is σ = 91814. Its totient is φ = 91812.

The previous prime is 91811. The next prime is 91823. The reversal of 91813 is 31819.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 91809 + 4 = 303^2 + 2^2 .

It is a cyclic number.

It is not a de Polignac number, because 91813 - 2¹ = 91811 is a prime.

Together with 91811, it forms a pair of twin primes.

91813 is a lucky number.

It is a zygodrome in base 3.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45906 + 45907.

It is an arithmetic number, because the mean of its divisors is an integer number (45907).

2⁹¹⁸¹³ is an apocalyptic number.

It is an amenable number.

91813 is a deficient number, since it is larger than the sum of its proper divisors (1).

91813 is an equidigital number, since it uses as much as digits as its factorization.

91813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 216, while the sum is 22.

The square root of 91813 is about 303.0066005882. The cubic root of 91813 is about 45.1129672006.

Adding to 91813 its product of digits (216), we get a palindrome (92029).

The spelling of 91813 in words is "ninety-one thousand, eight hundred thirteen".