21241312621 has 2 divisors, whose sum is σ = 21241312622. Its totient is φ = 21241312620.

The previous prime is 21241312619. The next prime is 21241312627. The reversal of 21241312621 is 12621314212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20229372900 + 1011939721 = 142230^2 + 31811^2 .

It is a cyclic number.

It is not a de Polignac number, because 21241312621 - 2¹ = 21241312619 is a prime.

Together with 21241312619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21241312627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620656310 + 10620656311.

It is an arithmetic number, because the mean of its divisors is an integer number (10620656311).

Almost surely, 2^21241312621 is an apocalyptic number.

It is an amenable number.

21241312621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21241312621 is an equidigital number, since it uses as much as digits as its factorization.

21241312621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 25.

Adding to 21241312621 its reverse (12621314212), we get a palindrome (33862626833).

The spelling of 21241312621 in words is "twenty-one billion, two hundred forty-one million, three hundred twelve thousand, six hundred twenty-one".