638378193121 has 2 divisors, whose sum is σ = 638378193122. Its totient is φ = 638378193120.

The previous prime is 638378193091. The next prime is 638378193151. The reversal of 638378193121 is 121391873836.

It is a balanced prime because it is at equal distance from previous prime (638378193091) and next prime (638378193151).

It can be written as a sum of positive squares in only one way, i.e., 628152938721 + 10225254400 = 792561^2 + 101120^2 .

It is a cyclic number.

It is not a de Polignac number, because 638378193121 - 2³⁹ = 88622379233 is a prime.

It is not a weakly prime, because it can be changed into another prime (638378193151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319189096560 + 319189096561.

It is an arithmetic number, because the mean of its divisors is an integer number (319189096561).

Almost surely, 2^638378193121 is an apocalyptic number.

It is an amenable number.

638378193121 is a deficient number, since it is larger than the sum of its proper divisors (1).

638378193121 is an equidigital number, since it uses as much as digits as its factorization.

638378193121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1306368, while the sum is 52.

The spelling of 638378193121 in words is "six hundred thirty-eight billion, three hundred seventy-eight million, one hundred ninety-three thousand, one hundred twenty-one".