26257866781 has 2 divisors, whose sum is σ = 26257866782. Its totient is φ = 26257866780.

The previous prime is 26257866743. The next prime is 26257866847. The reversal of 26257866781 is 18766875262.

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., 16407304281 + 9850562500 = 128091^2 + 99250^2 .

It is a cyclic number.

It is not a de Polignac number, because 26257866781 - 2¹⁹ = 26257342493 is a prime.

It is a super-2 number, since 2×26257866781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (26257866281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13128933390 + 13128933391.

It is an arithmetic number, because the mean of its divisors is an integer number (13128933391).

Almost surely, 2^26257866781 is an apocalyptic number.

It is an amenable number.

26257866781 is a deficient number, since it is larger than the sum of its proper divisors (1).

26257866781 is an equidigital number, since it uses as much as digits as its factorization.

26257866781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13547520, while the sum is 58.

The spelling of 26257866781 in words is "twenty-six billion, two hundred fifty-seven million, eight hundred sixty-six thousand, seven hundred eighty-one".