199999990 has 8 divisors (see below), whose sum is σ = 360000000. Its totient is φ = 79999992.

The previous prime is 199999963. The next prime is 199999991. The reversal of 199999990 is 99999991.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199999991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9999990 + ... + 10000009.

It is an arithmetic number, because the mean of its divisors is an integer number (45000000).

Almost surely, 2^199999990 is an apocalyptic number.

199999990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

199999990 is a deficient number, since it is larger than the sum of its proper divisors (160000010).

199999990 is a wasteful number, since it uses less digits than its factorization.

199999990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20000006.

The product of its (nonzero) digits is 4782969, while the sum is 64.

The square root of 199999990 is about 14142.1352701776. The cubic root of 199999990 is about 584.8035378958.

Subtracting from 199999990 its reverse (99999991), we obtain a palindrome (99999999).

The spelling of 199999990 in words is "one hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety".