91805261 has 2 divisors, whose sum is σ = 91805262. Its totient is φ = 91805260.

The previous prime is 91805243. The next prime is 91805269. The reversal of 91805261 is 16250819.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58049161 + 33756100 = 7619^2 + 5810^2 .

It is a cyclic number.

It is not a de Polignac number, because 91805261 - 2¹⁴ = 91788877 is a prime.

It is equal to p_5315648 and since 91805261 and 5315648 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91805269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45902630 + 45902631.

It is an arithmetic number, because the mean of its divisors is an integer number (45902631).

Almost surely, 2^91805261 is an apocalyptic number.

It is an amenable number.

91805261 is a deficient number, since it is larger than the sum of its proper divisors (1).

91805261 is an equidigital number, since it uses as much as digits as its factorization.

91805261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 91805261 is about 9581.5061968357. The cubic root of 91805261 is about 451.1169962756.

It can be divided in two parts, 9180 and 5261, that added together give a palindrome (14441).

The spelling of 91805261 in words is "ninety-one million, eight hundred five thousand, two hundred sixty-one".