199991387 has 2 divisors, whose sum is σ = 199991388. Its totient is φ = 199991386.

The previous prime is 199991381. The next prime is 199991411. The reversal of 199991387 is 783199991.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199991387 is a prime.

It is not a weakly prime, because it can be changed into another prime (199991381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99995693 + 99995694.

It is an arithmetic number, because the mean of its divisors is an integer number (99995694).

Almost surely, 2^199991387 is an apocalyptic number.

199991387 is a deficient number, since it is larger than the sum of its proper divisors (1).

199991387 is an equidigital number, since it uses as much as digits as its factorization.

199991387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1102248, while the sum is 56.

The square root of 199991387 is about 14141.8311049171. The cubic root of 199991387 is about 584.7951526671.

The spelling of 199991387 in words is "one hundred ninety-nine million, nine hundred ninety-one thousand, three hundred eighty-seven".