1999997777 has 2 divisors, whose sum is σ = 1999997778. Its totient is φ = 1999997776.

The previous prime is 1999997773. The next prime is 1999997807. The reversal of 1999997777 is 7777999991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1961072656 + 38925121 = 44284^2 + 6239^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999997777 - 2² = 1999997773 is a prime.

It is a super-2 number, since 2×1999997777² = 7999982216009883458, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1999997773) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999998888 + 999998889.

It is an arithmetic number, because the mean of its divisors is an integer number (999998889).

Almost surely, 2^1999997777 is an apocalyptic number.

It is an amenable number.

1999997777 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999997777 is an equidigital number, since it uses as much as digits as its factorization.

1999997777 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 141776649, while the sum is 74.

The square root of 1999997777 is about 44721.3346960933. The cubic root of 1999997777 is about 1259.9205830940.

The spelling of 1999997777 in words is "one billion, nine hundred ninety-nine million, nine hundred ninety-seven thousand, seven hundred seventy-seven".