91009998 has 24 divisors (see below), whose sum is σ = 199567368. Its totient is φ = 29970672.

The previous prime is 91009991. The next prime is 91010009. The reversal of 91009998 is 89990019.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91009991) 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, 28965 + ... + 31952.

It is an arithmetic number, because the mean of its divisors is an integer number (8315307).

Almost surely, 2^91009998 is an apocalyptic number.

91009998 is an abundant number, since it is smaller than the sum of its proper divisors (108557370).

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

91009998 is a wasteful number, since it uses less digits than its factorization.

91009998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61008 (or 61005 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 45.

The square root of 91009998 is about 9539.9160373664. The cubic root of 91009998 is about 449.8106166051.

The spelling of 91009998 in words is "ninety-one million, nine thousand, nine hundred ninety-eight".