6513765221 has 2 divisors, whose sum is σ = 6513765222. Its totient is φ = 6513765220.

The previous prime is 6513765199. The next prime is 6513765241. The reversal of 6513765221 is 1225673156.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6046773121 + 466992100 = 77761^2 + 21610^2 .

It is a cyclic number.

It is not a de Polignac number, because 6513765221 - 2¹⁸ = 6513503077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6513765241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3256882610 + 3256882611.

It is an arithmetic number, because the mean of its divisors is an integer number (3256882611).

Almost surely, 2^6513765221 is an apocalyptic number.

It is an amenable number.

6513765221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6513765221 is an equidigital number, since it uses as much as digits as its factorization.

6513765221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75600, while the sum is 38.

The square root of 6513765221 is about 80707.9006107828. The cubic root of 6513765221 is about 1867.5720557111.

The spelling of 6513765221 in words is "six billion, five hundred thirteen million, seven hundred sixty-five thousand, two hundred twenty-one".