1280265818581 has 2 divisors, whose sum is σ = 1280265818582. Its totient is φ = 1280265818580.

The previous prime is 1280265818483. The next prime is 1280265818603. The reversal of 1280265818581 is 1858185620821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 660629209681 + 619636608900 = 812791^2 + 787170^2 .

It is an emirp because it is prime and its reverse (1858185620821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1280265818581 - 2¹³ = 1280265810389 is a prime.

It is a super-2 number, since 2×1280265818581² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1280265818281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 640132909290 + 640132909291.

It is an arithmetic number, because the mean of its divisors is an integer number (640132909291).

Almost surely, 2^{1280265818581} is an apocalyptic number.

It is an amenable number.

1280265818581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1280265818581 is an equidigital number, since it uses as much as digits as its factorization.

1280265818581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2457600, while the sum is 55.

The spelling of 1280265818581 in words is "one trillion, two hundred eighty billion, two hundred sixty-five million, eight hundred eighteen thousand, five hundred eighty-one".