89999991 has 20 divisors (see below), whose sum is σ = 135036000. Its totient is φ = 59736096.

The previous prime is 89999983. The next prime is 89999999. The reversal of 89999991 is 19999998.

It is an interprime number because it is at equal distance from previous prime (89999983) and next prime (89999999).

It is not a de Polignac number, because 89999991 - 2³ = 89999983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (89999999) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 17035 + ... + 21683.

It is an arithmetic number, because the mean of its divisors is an integer number (6751800).

Almost surely, 2^89999991 is an apocalyptic number.

89999991 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

89999991 is a deficient number, since it is larger than the sum of its proper divisors (45036009).

89999991 is a wasteful number, since it uses less digits than its factorization.

89999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4900 (or 4891 counting only the distinct ones).

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

The square root of 89999991 is about 9486.8325061635. The cubic root of 89999991 is about 448.1404597177.

It can be divided in two parts, 8999999 and 1, that added together give a square (9000000 = 3000²).

The spelling of 89999991 in words is "eighty-nine million, nine hundred ninety-nine thousand, nine hundred ninety-one".