98999991 has 12 divisors (see below), whose sum is σ = 143287560. Its totient is φ = 65867280.

The previous prime is 98999987. The next prime is 99000007. The reversal of 98999991 is 19999989.

It is not a de Polignac number, because 98999991 - 2² = 98999987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (98999911) 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, 6225 + ... + 15386.

It is an arithmetic number, because the mean of its divisors is an integer number (11940630).

Almost surely, 2^98999991 is an apocalyptic number.

98999991 is a deficient number, since it is larger than the sum of its proper divisors (44287569).

98999991 is a wasteful number, since it uses less digits than its factorization.

98999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22126 (or 22123 counting only the distinct ones).

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

The square root of 98999991 is about 9949.8739187992. The cubic root of 98999991 is about 462.6064868999.

It can be divided in two parts, 9 and 8999991, that added together give a square (9000000 = 3000²).

The spelling of 98999991 in words is "ninety-eight million, nine hundred ninety-nine thousand, nine hundred ninety-one".