91097987 has 2 divisors, whose sum is σ = 91097988. Its totient is φ = 91097986.

The previous prime is 91097971. The next prime is 91098031. The reversal of 91097987 is 78979019.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91097987 - 2⁴ = 91097971 is a prime.

It is not a weakly prime, because it can be changed into another prime (91097087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45548993 + 45548994.

It is an arithmetic number, because the mean of its divisors is an integer number (45548994).

Almost surely, 2^91097987 is an apocalyptic number.

91097987 is a deficient number, since it is larger than the sum of its proper divisors (1).

91097987 is an equidigital number, since it uses as much as digits as its factorization.

91097987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 285768, while the sum is 50.

The square root of 91097987 is about 9544.5265466654. The cubic root of 91097987 is about 449.9555297619.

The spelling of 91097987 in words is "ninety-one million, ninety-seven thousand, nine hundred eighty-seven".