199991557 has 2 divisors, whose sum is σ = 199991558. Its totient is φ = 199991556.

The previous prime is 199991531. The next prime is 199991567. The reversal of 199991557 is 755199991.

199991557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127554436 + 72437121 = 11294^2 + 8511^2 .

It is a cyclic number.

It is not a de Polignac number, because 199991557 - 2¹¹ = 199989509 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 199991498 and 199991507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199991527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99995778 + 99995779.

It is an arithmetic number, because the mean of its divisors is an integer number (99995779).

Almost surely, 2^199991557 is an apocalyptic number.

It is an amenable number.

199991557 is a deficient number, since it is larger than the sum of its proper divisors (1).

199991557 is an equidigital number, since it uses as much as digits as its factorization.

199991557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1148175, while the sum is 55.

The square root of 199991557 is about 14141.8371154529. The cubic root of 199991557 is about 584.7953183662.

The spelling of 199991557 in words is "one hundred ninety-nine million, nine hundred ninety-one thousand, five hundred fifty-seven".