7777421856817 has 2 divisors, whose sum is σ = 7777421856818. Its totient is φ = 7777421856816.

The previous prime is 7777421856811. The next prime is 7777421856839. The reversal of 7777421856817 is 7186581247777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7080048218896 + 697373637921 = 2660836^2 + 835089^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7777421856817 is a prime.

It is not a weakly prime, because it can be changed into another prime (7777421856811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3888710928408 + 3888710928409.

It is an arithmetic number, because the mean of its divisors is an integer number (3888710928409).

Almost surely, 2^{7777421856817} is an apocalyptic number.

It is an amenable number.

7777421856817 is a deficient number, since it is larger than the sum of its proper divisors (1).

7777421856817 is an equidigital number, since it uses as much as digits as its factorization.

7777421856817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 258155520, while the sum is 70.

The spelling of 7777421856817 in words is "seven trillion, seven hundred seventy-seven billion, four hundred twenty-one million, eight hundred fifty-six thousand, eight hundred seventeen".