91440256993 has 2 divisors, whose sum is σ = 91440256994. Its totient is φ = 91440256992.

The previous prime is 91440256949. The next prime is 91440257059. The reversal of 91440256993 is 39965204419.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66155440849 + 25284816144 = 257207^2 + 159012^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91440256993 is a prime.

It is a super-2 number, since 2×91440256993² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 91440256993.

It is not a weakly prime, because it can be changed into another prime (91440256093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45720128496 + 45720128497.

It is an arithmetic number, because the mean of its divisors is an integer number (45720128497).

Almost surely, 2^91440256993 is an apocalyptic number.

It is an amenable number.

91440256993 is a deficient number, since it is larger than the sum of its proper divisors (1).

91440256993 is an equidigital number, since it uses as much as digits as its factorization.

91440256993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2099520, while the sum is 52.

The spelling of 91440256993 in words is "ninety-one billion, four hundred forty million, two hundred fifty-six thousand, nine hundred ninety-three".