205199056781 has 2 divisors, whose sum is σ = 205199056782. Its totient is φ = 205199056780.

The previous prime is 205199056771. The next prime is 205199056793. The reversal of 205199056781 is 187650991502.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 119194110025 + 86004946756 = 345245^2 + 293266^2 .

It is a cyclic number.

It is not a de Polignac number, because 205199056781 - 2¹⁸ = 205198794637 is a prime.

It is a super-2 number, since 2×205199056781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205199056771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102599528390 + 102599528391.

It is an arithmetic number, because the mean of its divisors is an integer number (102599528391).

Almost surely, 2^205199056781 is an apocalyptic number.

It is an amenable number.

205199056781 is a deficient number, since it is larger than the sum of its proper divisors (1).

205199056781 is an equidigital number, since it uses as much as digits as its factorization.

205199056781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1360800, while the sum is 53.

The spelling of 205199056781 in words is "two hundred five billion, one hundred ninety-nine million, fifty-six thousand, seven hundred eighty-one".