91511521 has 2 divisors, whose sum is σ = 91511522. Its totient is φ = 91511520.

The previous prime is 91511509. The next prime is 91511531. The reversal of 91511521 is 12511519.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91107025 + 404496 = 9545^2 + 636^2 .

It is a cyclic number.

It is not a de Polignac number, because 91511521 - 2⁵ = 91511489 is a prime.

It is not a weakly prime, because it can be changed into another prime (91511531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45755760 + 45755761.

It is an arithmetic number, because the mean of its divisors is an integer number (45755761).

Almost surely, 2^91511521 is an apocalyptic number.

It is an amenable number.

91511521 is a deficient number, since it is larger than the sum of its proper divisors (1).

91511521 is an equidigital number, since it uses as much as digits as its factorization.

91511521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 450, while the sum is 25.

The square root of 91511521 is about 9566.1654282163. The cubic root of 91511521 is about 450.6353510908.

The spelling of 91511521 in words is "ninety-one million, five hundred eleven thousand, five hundred twenty-one".