91215689 has 2 divisors, whose sum is σ = 91215690. Its totient is φ = 91215688.

The previous prime is 91215653. The next prime is 91215721. The reversal of 91215689 is 98651219.

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., 61152400 + 30063289 = 7820^2 + 5483^2 .

It is a cyclic number.

It is not a de Polignac number, because 91215689 - 2⁸ = 91215433 is a prime.

It is not a weakly prime, because it can be changed into another prime (91215629) 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, 45607844 + 45607845.

It is an arithmetic number, because the mean of its divisors is an integer number (45607845).

Almost surely, 2^91215689 is an apocalyptic number.

It is an amenable number.

91215689 is a deficient number, since it is larger than the sum of its proper divisors (1).

91215689 is an equidigital number, since it uses as much as digits as its factorization.

91215689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 41.

The square root of 91215689 is about 9550.6904985975. The cubic root of 91215689 is about 450.1492328092.

The spelling of 91215689 in words is "ninety-one million, two hundred fifteen thousand, six hundred eighty-nine".