91997687 has 2 divisors, whose sum is σ = 91997688. Its totient is φ = 91997686.

The previous prime is 91997669. The next prime is 91997743. The reversal of 91997687 is 78679919.

It is an a-pointer prime, because the next prime (91997743) can be obtained adding 91997687 to its sum of digits (56).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91997687 - 2⁶ = 91997623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91997617) 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, 45998843 + 45998844.

It is an arithmetic number, because the mean of its divisors is an integer number (45998844).

Almost surely, 2^91997687 is an apocalyptic number.

91997687 is a deficient number, since it is larger than the sum of its proper divisors (1).

91997687 is an equidigital number, since it uses as much as digits as its factorization.

91997687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1714608, while the sum is 56.

The square root of 91997687 is about 9591.5424724077. The cubic root of 91997687 is about 451.4319602879.

The spelling of 91997687 in words is "ninety-one million, nine hundred ninety-seven thousand, six hundred eighty-seven".