99999999809 has 4 divisors (see below), whose sum is σ = 101694915120. Its totient is φ = 98305084500.

The previous prime is 99999999769. The next prime is 99999999821. The reversal of 99999999809 is 90899999999.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 99999999809 - 2²⁴ = 99983222593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99999999829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 847457567 + ... + 847457684.

It is an arithmetic number, because the mean of its divisors is an integer number (25423728780).

Almost surely, 2^99999999809 is an apocalyptic number.

It is an amenable number.

99999999809 is a deficient number, since it is larger than the sum of its proper divisors (1694915311).

99999999809 is a wasteful number, since it uses less digits than its factorization.

99999999809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1694915310.

The product of its (nonzero) digits is 3099363912, while the sum is 89.

The spelling of 99999999809 in words is "ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred nine".