21013210213081 has 2 divisors, whose sum is σ = 21013210213082. Its totient is φ = 21013210213080.

The previous prime is 21013210213069. The next prime is 21013210213199. The reversal of 21013210213081 is 18031201231012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20203901265625 + 809308947456 = 4494875^2 + 899616^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013210213081 - 2⁹ = 21013210212569 is a prime.

It is a super-2 number, since 2×21013210213081² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21013210213031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506605106540 + 10506605106541.

It is an arithmetic number, because the mean of its divisors is an integer number (10506605106541).

Almost surely, 2^{21013210213081} is an apocalyptic number.

It is an amenable number.

21013210213081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013210213081 is an equidigital number, since it uses as much as digits as its factorization.

21013210213081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 25.

Adding to 21013210213081 its reverse (18031201231012), we get a palindrome (39044411444093).

The spelling of 21013210213081 in words is "twenty-one trillion, thirteen billion, two hundred ten million, two hundred thirteen thousand, eighty-one".