209999747977 has 2 divisors, whose sum is σ = 209999747978. Its totient is φ = 209999747976.

The previous prime is 209999747963. The next prime is 209999747981. The reversal of 209999747977 is 779747999902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 153923613561 + 56076134416 = 392331^2 + 236804^2 .

It is a cyclic number.

It is not a de Polignac number, because 209999747977 - 2¹¹ = 209999745929 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 209999747897 and 209999747906.

It is not a weakly prime, because it can be changed into another prime (209999747957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104999873988 + 104999873989.

It is an arithmetic number, because the mean of its divisors is an integer number (104999873989).

Almost surely, 2^209999747977 is an apocalyptic number.

It is an amenable number.

209999747977 is a deficient number, since it is larger than the sum of its proper divisors (1).

209999747977 is an equidigital number, since it uses as much as digits as its factorization.

209999747977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1134213192, while the sum is 79.

The spelling of 209999747977 in words is "two hundred nine billion, nine hundred ninety-nine million, seven hundred forty-seven thousand, nine hundred seventy-seven".