21256080281 has 2 divisors, whose sum is σ = 21256080282. Its totient is φ = 21256080280.

The previous prime is 21256080247. The next prime is 21256080301. The reversal of 21256080281 is 18208065212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12891331600 + 8364748681 = 113540^2 + 91459^2 .

It is a cyclic number.

It is not a de Polignac number, because 21256080281 - 2¹⁸ = 21255818137 is a prime.

It is a super-2 number, since 2×21256080281² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21256080481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10628040140 + 10628040141.

It is an arithmetic number, because the mean of its divisors is an integer number (10628040141).

Almost surely, 2^21256080281 is an apocalyptic number.

It is an amenable number.

21256080281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21256080281 is an equidigital number, since it uses as much as digits as its factorization.

21256080281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15360, while the sum is 35.

The spelling of 21256080281 in words is "twenty-one billion, two hundred fifty-six million, eighty thousand, two hundred eighty-one".