91393681 has 2 divisors, whose sum is σ = 91393682. Its totient is φ = 91393680.

The previous prime is 91393661. The next prime is 91393693. The reversal of 91393681 is 18639319.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91393600 + 81 = 9560^2 + 9^2 .

It is an emirp because it is prime and its reverse (18639319) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91393681 - 2¹¹ = 91391633 is a prime.

It is a super-2 number, since 2×91393681² = 16705609853459522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (91393661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45696840 + 45696841.

It is an arithmetic number, because the mean of its divisors is an integer number (45696841).

Almost surely, 2^91393681 is an apocalyptic number.

It is an amenable number.

91393681 is a deficient number, since it is larger than the sum of its proper divisors (1).

91393681 is an equidigital number, since it uses as much as digits as its factorization.

91393681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34992, while the sum is 40.

The square root of 91393681 is about 9560.0042364007. The cubic root of 91393681 is about 450.4418392825.

It can be divided in two parts, 913936 and 81, that multiplied together give a square (74028816 = 8604²).

The spelling of 91393681 in words is "ninety-one million, three hundred ninety-three thousand, six hundred eighty-one".