99810091 has 4 divisors (see below), whose sum is σ = 101446384. Its totient is φ = 98173800.

The previous prime is 99810047. The next prime is 99810121. The reversal of 99810091 is 19001899.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19001899 = 7 ⋅2714557.

It is a cyclic number.

It is not a de Polignac number, because 99810091 - 2¹⁹ = 99285803 is a prime.

It is the 9991-st Hogben number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 99810091.

It is not an unprimeable number, because it can be changed into a prime (99810001) by changing a digit.

It is a nontrivial repunit in base 9990.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 818055 + ... + 818176.

It is an arithmetic number, because the mean of its divisors is an integer number (25361596).

Almost surely, 2^99810091 is an apocalyptic number.

99810091 is a deficient number, since it is larger than the sum of its proper divisors (1636293).

99810091 is a wasteful number, since it uses less digits than its factorization.

99810091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1636292.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 99810091 is about 9990.5000375357. The cubic root of 99810091 is about 463.8648706659.

The spelling of 99810091 in words is "ninety-nine million, eight hundred ten thousand, ninety-one".