91097988 has 12 divisors (see below), whose sum is σ = 212562000. Its totient is φ = 30365992.

The previous prime is 91097987. The next prime is 91098031. The reversal of 91097988 is 88979019.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 91097988.

It is not an unprimeable number, because it can be changed into a prime (91097987) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3795738 + ... + 3795761.

It is an arithmetic number, because the mean of its divisors is an integer number (17713500).

Almost surely, 2^91097988 is an apocalyptic number.

It is an amenable number.

91097988 is an abundant number, since it is smaller than the sum of its proper divisors (121464012).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91097988 is a wasteful number, since it uses less digits than its factorization.

91097988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7591506 (or 7591504 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 51.

The square root of 91097988 is about 9544.5265990514. The cubic root of 91097988 is about 449.9555314083.

The spelling of 91097988 in words is "ninety-one million, ninety-seven thousand, nine hundred eighty-eight".