6517421621 has 2 divisors, whose sum is σ = 6517421622. Its totient is φ = 6517421620.

The previous prime is 6517421593. The next prime is 6517421693. The reversal of 6517421621 is 1261247156.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3698342596 + 2819079025 = 60814^2 + 53095^2 .

It is a cyclic number.

It is not a de Polignac number, because 6517421621 - 2¹⁰ = 6517420597 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6517451621) 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, 3258710810 + 3258710811.

It is an arithmetic number, because the mean of its divisors is an integer number (3258710811).

Almost surely, 2^6517421621 is an apocalyptic number.

It is an amenable number.

6517421621 is a deficient number, since it is larger than the sum of its proper divisors (1).

6517421621 is an equidigital number, since it uses as much as digits as its factorization.

6517421621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 35.

The square root of 6517421621 is about 80730.5494902642. The cubic root of 6517421621 is about 1867.9214344459.

Adding to 6517421621 its reverse (1261247156), we get a palindrome (7778668777).

The spelling of 6517421621 in words is "six billion, five hundred seventeen million, four hundred twenty-one thousand, six hundred twenty-one".