99999809 has 16 divisors (see below), whose sum is σ = 123459840. Its totient is φ = 78874560.

The previous prime is 99999787. The next prime is 99999821. The reversal of 99999809 is 90899999.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99999809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (99999839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31139 + ... + 34199.

It is an arithmetic number, because the mean of its divisors is an integer number (7716240).

Almost surely, 2^99999809 is an apocalyptic number.

It is an amenable number.

99999809 is a deficient number, since it is larger than the sum of its proper divisors (23460031).

99999809 is a wasteful number, since it uses less digits than its factorization.

99999809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3440.

The product of its (nonzero) digits is 4251528, while the sum is 62.

The square root of 99999809 is about 9999.9904499954. The cubic root of 99999809 is about 464.1585878466.

The spelling of 99999809 in words is "ninety-nine million, nine hundred ninety-nine thousand, eight hundred nine".