91221307 has 2 divisors, whose sum is σ = 91221308. Its totient is φ = 91221306.

The previous prime is 91221217. The next prime is 91221323. The reversal of 91221307 is 70312219.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91221307 is a prime.

It is not a weakly prime, because it can be changed into another prime (91221367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45610653 + 45610654.

It is an arithmetic number, because the mean of its divisors is an integer number (45610654).

Almost surely, 2^91221307 is an apocalyptic number.

91221307 is a deficient number, since it is larger than the sum of its proper divisors (1).

91221307 is an equidigital number, since it uses as much as digits as its factorization.

91221307 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 91221307 is about 9550.9846089291. The cubic root of 91221307 is about 450.1584742255.

The spelling of 91221307 in words is "ninety-one million, two hundred twenty-one thousand, three hundred seven".