99990809 has 4 divisors (see below), whose sum is σ = 100033716. Its totient is φ = 99947904.

The previous prime is 99990799. The next prime is 99990871. The reversal of 99990809 is 90809999.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43033600 + 56957209 = 6560^2 + 7547^2 .

It is a cyclic number.

It is not a de Polignac number, because 99990809 - 2²⁴ = 83213593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99590809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17744 + ... + 22689.

It is an arithmetic number, because the mean of its divisors is an integer number (25008429).

Almost surely, 2^99990809 is an apocalyptic number.

It is an amenable number.

99990809 is a deficient number, since it is larger than the sum of its proper divisors (42907).

99990809 is a wasteful number, since it uses less digits than its factorization.

99990809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42906.

The product of its (nonzero) digits is 472392, while the sum is 53.

The square root of 99990809 is about 9999.5404394402. The cubic root of 99990809 is about 464.1446626446.

The spelling of 99990809 in words is "ninety-nine million, nine hundred ninety thousand, eight hundred nine".