199749989 has 2 divisors, whose sum is σ = 199749990. Its totient is φ = 199749988.

The previous prime is 199749961. The next prime is 199749997. The reversal of 199749989 is 989947991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 195580225 + 4169764 = 13985^2 + 2042^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199749989 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199749919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99874994 + 99874995.

It is an arithmetic number, because the mean of its divisors is an integer number (99874995).

Almost surely, 2^199749989 is an apocalyptic number.

It is an amenable number.

199749989 is a deficient number, since it is larger than the sum of its proper divisors (1).

199749989 is an equidigital number, since it uses as much as digits as its factorization.

199749989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13226976, while the sum is 65.

The square root of 199749989 is about 14133.2936359505. The cubic root of 199749989 is about 584.5597671684.

The spelling of 199749989 in words is "one hundred ninety-nine million, seven hundred forty-nine thousand, nine hundred eighty-nine".