199809905 has 8 divisors (see below), whose sum is σ = 239870592. Its totient is φ = 159782128.

The previous prime is 199809893. The next prime is 199809923. The reversal of 199809905 is 509908991.

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

It is a cyclic number.

It is not a de Polignac number, because 199809905 - 2⁴ = 199809889 is a prime.

It is a super-2 number, since 2×199809905² = 79847996272218050, which contains 22 as substring.

It is a Duffinian 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 7 ways as a sum of consecutive naturals, for example, 8072 + ... + 21558.

It is an arithmetic number, because the mean of its divisors is an integer number (29983824).

Almost surely, 2^199809905 is an apocalyptic number.

It is an amenable number.

199809905 is a deficient number, since it is larger than the sum of its proper divisors (40060687).

199809905 is a wasteful number, since it uses less digits than its factorization.

199809905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16455.

The product of its (nonzero) digits is 262440, while the sum is 50.

The square root of 199809905 is about 14135.4131527876. The cubic root of 199809905 is about 584.6182085261.

The spelling of 199809905 in words is "one hundred ninety-nine million, eight hundred nine thousand, nine hundred five".