6421056557 has 2 divisors, whose sum is σ = 6421056558. Its totient is φ = 6421056556.

The previous prime is 6421056497. The next prime is 6421056559. The reversal of 6421056557 is 7556501246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6164448196 + 256608361 = 78514^2 + 16019^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6421056557 is a prime.

Together with 6421056559, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6421056559) 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, 3210528278 + 3210528279.

It is an arithmetic number, because the mean of its divisors is an integer number (3210528279).

Almost surely, 2^6421056557 is an apocalyptic number.

It is an amenable number.

6421056557 is a deficient number, since it is larger than the sum of its proper divisors (1).

6421056557 is an equidigital number, since it uses as much as digits as its factorization.

6421056557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252000, while the sum is 41.

The square root of 6421056557 is about 80131.4954122285. The cubic root of 6421056557 is about 1858.6694686288.

The spelling of 6421056557 in words is "six billion, four hundred twenty-one million, fifty-six thousand, five hundred fifty-seven".