668239427861 has 2 divisors, whose sum is σ = 668239427862. Its totient is φ = 668239427860.

The previous prime is 668239427827. The next prime is 668239427879. The reversal of 668239427861 is 168724932866.

668239427861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 667333779025 + 905648836 = 816905^2 + 30094^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668239427861 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 668239427794 and 668239427803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668239427561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334119713930 + 334119713931.

It is an arithmetic number, because the mean of its divisors is an integer number (334119713931).

Almost surely, 2^668239427861 is an apocalyptic number.

It is an amenable number.

668239427861 is a deficient number, since it is larger than the sum of its proper divisors (1).

668239427861 is an equidigital number, since it uses as much as digits as its factorization.

668239427861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41803776, while the sum is 62.

The spelling of 668239427861 in words is "six hundred sixty-eight billion, two hundred thirty-nine million, four hundred twenty-seven thousand, eight hundred sixty-one".