99991806 has 8 divisors (see below), whose sum is σ = 199983624. Its totient is φ = 33330600.

The previous prime is 99991789. The next prime is 99991819. The reversal of 99991806 is 60819999.

It is a sphenic number, since it is the product of 3 distinct primes.

99991806 is an admirable number.

It is a super-2 number, since 2×99991806² = 19996722534283272, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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, 8332645 + ... + 8332656.

It is an arithmetic number, because the mean of its divisors is an integer number (24997953).

Almost surely, 2^99991806 is an apocalyptic number.

99991806 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

99991806 is a wasteful number, since it uses less digits than its factorization.

99991806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16665306.

The product of its (nonzero) digits is 314928, while the sum is 51.

The square root of 99991806 is about 9999.5902916070. The cubic root of 99991806 is about 464.1462052887.

The spelling of 99991806 in words is "ninety-nine million, nine hundred ninety-one thousand, eight hundred six".