99811 has 4 divisors (see below), whose sum is σ = 100624. Its totient is φ = 99000.

The previous prime is 99809. The next prime is 99817. The reversal of 99811 is 11899.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 11899 = 73 ⋅163.

It is a cyclic number.

It is not a de Polignac number, because 99811 - 2¹ = 99809 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 99811.

It is not an unprimeable number, because it can be changed into a prime (99817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 180 + ... + 481.

It is an arithmetic number, because the mean of its divisors is an integer number (25156).

2⁹⁹⁸¹¹ is an apocalyptic number.

99811 is a deficient number, since it is larger than the sum of its proper divisors (813).

99811 is a wasteful number, since it uses less digits than its factorization.

99811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 812.

The product of its digits is 648, while the sum is 28.

The square root of 99811 is about 315.9287894447. The cubic root of 99811 is about 46.3866278846.

The spelling of 99811 in words is "ninety-nine thousand, eight hundred eleven".