6518911621 has 2 divisors, whose sum is σ = 6518911622. Its totient is φ = 6518911620.

The previous prime is 6518911603. The next prime is 6518911657. The reversal of 6518911621 is 1261198156.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6490074721 + 28836900 = 80561^2 + 5370^2 .

It is a cyclic number.

It is not a de Polignac number, because 6518911621 - 2⁹ = 6518911109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6518911691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3259455810 + 3259455811.

It is an arithmetic number, because the mean of its divisors is an integer number (3259455811).

Almost surely, 2^6518911621 is an apocalyptic number.

It is an amenable number.

6518911621 is a deficient number, since it is larger than the sum of its proper divisors (1).

6518911621 is an equidigital number, since it uses as much as digits as its factorization.

6518911621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 40.

The square root of 6518911621 is about 80739.7771919145. Note that the first 3 decimals coincide. The cubic root of 6518911621 is about 1868.0637704303.

The spelling of 6518911621 in words is "six billion, five hundred eighteen million, nine hundred eleven thousand, six hundred twenty-one".