638660276861 has 2 divisors, whose sum is σ = 638660276862. Its totient is φ = 638660276860.

The previous prime is 638660276773. The next prime is 638660276869. The reversal of 638660276861 is 168672066836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 637092908761 + 1567368100 = 798181^2 + 39590^2 .

It is a cyclic number.

It is not a de Polignac number, because 638660276861 - 2¹⁰ = 638660275837 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638660276861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638660276869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319330138430 + 319330138431.

It is an arithmetic number, because the mean of its divisors is an integer number (319330138431).

Almost surely, 2^638660276861 is an apocalyptic number.

It is an amenable number.

638660276861 is a deficient number, since it is larger than the sum of its proper divisors (1).

638660276861 is an equidigital number, since it uses as much as digits as its factorization.

638660276861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20901888, while the sum is 59.

The spelling of 638660276861 in words is "six hundred thirty-eight billion, six hundred sixty million, two hundred seventy-six thousand, eight hundred sixty-one".