265378777681 has 2 divisors, whose sum is σ = 265378777682. Its totient is φ = 265378777680.

The previous prime is 265378777619. The next prime is 265378777711. The reversal of 265378777681 is 186777873562.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208589504656 + 56789273025 = 456716^2 + 238305^2 .

It is a cyclic number.

It is not a de Polignac number, because 265378777681 - 2¹¹ = 265378775633 is a prime.

It is a super-2 number, since 2×265378777681² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (265378777481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 132689388840 + 132689388841.

It is an arithmetic number, because the mean of its divisors is an integer number (132689388841).

Almost surely, 2^265378777681 is an apocalyptic number.

It is an amenable number.

265378777681 is a deficient number, since it is larger than the sum of its proper divisors (1).

265378777681 is an equidigital number, since it uses as much as digits as its factorization.

265378777681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165957120, while the sum is 67.

The spelling of 265378777681 in words is "two hundred sixty-five billion, three hundred seventy-eight million, seven hundred seventy-seven thousand, six hundred eighty-one".