6517421681 has 4 divisors (see below), whose sum is σ = 6578332272. Its totient is φ = 6456511092.

The previous prime is 6517421621. The next prime is 6517421693. The reversal of 6517421681 is 1861247156.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6517421681 is a prime.

It is a super-2 number, since 2×6517421681² = 84953570735937731522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6517421621) 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 in 3 ways as a sum of consecutive naturals, for example, 30455135 + ... + 30455348.

It is an arithmetic number, because the mean of its divisors is an integer number (1644583068).

Almost surely, 2^6517421681 is an apocalyptic number.

It is an amenable number.

6517421681 is a deficient number, since it is larger than the sum of its proper divisors (60910591).

6517421681 is a wasteful number, since it uses less digits than its factorization.

6517421681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60910590.

The product of its digits is 80640, while the sum is 41.

The square root of 6517421681 is about 80730.5498618708. The cubic root of 6517421681 is about 1867.9214401780.

The spelling of 6517421681 in words is "six billion, five hundred seventeen million, four hundred twenty-one thousand, six hundred eighty-one".