199977779 has 2 divisors, whose sum is σ = 199977780. Its totient is φ = 199977778.

The previous prime is 199977773. The next prime is 199977797. The reversal of 199977779 is 977779991.

Together with next prime (199977797) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is an emirp because it is prime and its reverse (977779991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199977779 - 2⁸ = 199977523 is a prime.

It is a super-2 number, since 2×199977779² = 79982224187545682, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (199977773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99988889 + 99988890.

It is an arithmetic number, because the mean of its divisors is an integer number (99988890).

Almost surely, 2^199977779 is an apocalyptic number.

199977779 is a deficient number, since it is larger than the sum of its proper divisors (1).

199977779 is an equidigital number, since it uses as much as digits as its factorization.

199977779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15752961, while the sum is 65.

The square root of 199977779 is about 14141.3499709186. The cubic root of 199977779 is about 584.7818886410.

The spelling of 199977779 in words is "one hundred ninety-nine million, nine hundred seventy-seven thousand, seven hundred seventy-nine".