6821279075557 has 2 divisors, whose sum is σ = 6821279075558. Its totient is φ = 6821279075556.

The previous prime is 6821279075519. The next prime is 6821279075579. The reversal of 6821279075557 is 7555709721286.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5660468922276 + 1160810153281 = 2379174^2 + 1077409^2 .

It is a cyclic number.

It is not a de Polignac number, because 6821279075557 - 2²⁷ = 6821144857829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6821279072557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3410639537778 + 3410639537779.

It is an arithmetic number, because the mean of its divisors is an integer number (3410639537779).

Almost surely, 2^{6821279075557} is an apocalyptic number.

It is an amenable number.

6821279075557 is a deficient number, since it is larger than the sum of its proper divisors (1).

6821279075557 is an equidigital number, since it uses as much as digits as its factorization.

6821279075557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 74088000, while the sum is 64.

The spelling of 6821279075557 in words is "six trillion, eight hundred twenty-one billion, two hundred seventy-nine million, seventy-five thousand, five hundred fifty-seven".