199193809 has 2 divisors, whose sum is σ = 199193810. Its totient is φ = 199193808.

The previous prime is 199193807. The next prime is 199193899. The reversal of 199193809 is 908391991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 127622209 + 71571600 = 11297^2 + 8460^2 .

It is a cyclic number.

It is not a de Polignac number, because 199193809 - 2¹ = 199193807 is a prime.

Together with 199193807, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (199193803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99596904 + 99596905.

It is an arithmetic number, because the mean of its divisors is an integer number (99596905).

Almost surely, 2^199193809 is an apocalyptic number.

It is an amenable number.

199193809 is a deficient number, since it is larger than the sum of its proper divisors (1).

199193809 is an equidigital number, since it uses as much as digits as its factorization.

199193809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 157464, while the sum is 49.

The square root of 199193809 is about 14113.6036858061. The cubic root of 199193809 is about 584.0167172061.

It can be divided in two parts, 199193 and 809, that added together give a palindrome (200002).

The spelling of 199193809 in words is "one hundred ninety-nine million, one hundred ninety-three thousand, eight hundred nine".