91999998 has 24 divisors (see below), whose sum is σ = 202714200. Its totient is φ = 30146544.

The previous prime is 91999993. The next prime is 92000011. The reversal of 91999998 is 89999919.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91999993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42253 + ... + 44376.

It is an arithmetic number, because the mean of its divisors is an integer number (8446425).

Almost surely, 2^91999998 is an apocalyptic number.

91999998 is an abundant number, since it is smaller than the sum of its proper divisors (110714202).

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

91999998 is a wasteful number, since it uses less digits than its factorization.

91999998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86696 (or 86693 counting only the distinct ones).

The product of its digits is 4251528, while the sum is 63.

The square root of 91999998 is about 9591.6629423682. The cubic root of 91999998 is about 451.4357402761.

The spelling of 91999998 in words is "ninety-one million, nine hundred ninety-nine thousand, nine hundred ninety-eight".