21311003281 has 2 divisors, whose sum is σ = 21311003282. Its totient is φ = 21311003280.

The previous prime is 21311003279. The next prime is 21311003297. The reversal of 21311003281 is 18230011312.

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., 13973367681 + 7337635600 = 118209^2 + 85660^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311003281 - 2¹ = 21311003279 is a prime.

It is a super-2 number, since 2×21311003281² (a number of 21 digits) contains 22 as substring.

Together with 21311003279, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21311003221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655501640 + 10655501641.

It is an arithmetic number, because the mean of its divisors is an integer number (10655501641).

Almost surely, 2^21311003281 is an apocalyptic number.

It is an amenable number.

21311003281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311003281 is an equidigital number, since it uses as much as digits as its factorization.

21311003281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 22.

Adding to 21311003281 its reverse (18230011312), we get a palindrome (39541014593).

The spelling of 21311003281 in words is "twenty-one billion, three hundred eleven million, three thousand, two hundred eighty-one".