199989857 has 2 divisors, whose sum is σ = 199989858. Its totient is φ = 199989856.

The previous prime is 199989827. The next prime is 199989859. The reversal of 199989857 is 758989991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 195328576 + 4661281 = 13976^2 + 2159^2 .

It is a cyclic number.

It is not a de Polignac number, because 199989857 - 2⁶ = 199989793 is a prime.

Together with 199989859, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 199989793 and 199989802.

It is not a weakly prime, because it can be changed into another prime (199989859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99994928 + 99994929.

It is an arithmetic number, because the mean of its divisors is an integer number (99994929).

Almost surely, 2^199989857 is an apocalyptic number.

It is an amenable number.

199989857 is a deficient number, since it is larger than the sum of its proper divisors (1).

199989857 is an equidigital number, since it uses as much as digits as its factorization.

199989857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14696640, while the sum is 65.

The square root of 199989857 is about 14141.7770099800. Note that the first 3 decimals coincide. The cubic root of 199989857 is about 584.7936613715.

The spelling of 199989857 in words is "one hundred ninety-nine million, nine hundred eighty-nine thousand, eight hundred fifty-seven".