91243989 has 20 divisors (see below), whose sum is σ = 137359200. Its totient is φ = 60357960.

The previous prime is 91243969. The next prime is 91243991. The reversal of 91243989 is 98934219.

It is not a de Polignac number, because 91243989 - 2¹² = 91239893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91243939) 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 in 19 ways as a sum of consecutive naturals, for example, 6312 + ... + 14910.

It is an arithmetic number, because the mean of its divisors is an integer number (6867960).

Almost surely, 2^91243989 is an apocalyptic number.

It is an amenable number.

91243989 is a deficient number, since it is larger than the sum of its proper divisors (46115211).

91243989 is a wasteful number, since it uses less digits than its factorization.

91243989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8742 (or 8733 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 91243989 is about 9552.1719519699. The cubic root of 91243989 is about 450.1957814757.

The spelling of 91243989 in words is "ninety-one million, two hundred forty-three thousand, nine hundred eighty-nine".