91023071521 has 2 divisors, whose sum is σ = 91023071522. Its totient is φ = 91023071520.

The previous prime is 91023071509. The next prime is 91023071609. The reversal of 91023071521 is 12517032019.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55054052496 + 35969019025 = 234636^2 + 189655^2 .

It is a cyclic number.

It is not a de Polignac number, because 91023071521 - 2⁷ = 91023071393 is a prime.

It is a super-3 number, since 3×91023071521³ (a number of 34 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (91023072521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45511535760 + 45511535761.

It is an arithmetic number, because the mean of its divisors is an integer number (45511535761).

Almost surely, 2^91023071521 is an apocalyptic number.

It is an amenable number.

91023071521 is a deficient number, since it is larger than the sum of its proper divisors (1).

91023071521 is an equidigital number, since it uses as much as digits as its factorization.

91023071521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 31.

The spelling of 91023071521 in words is "ninety-one billion, twenty-three million, seventy-one thousand, five hundred twenty-one".