638155551889 has 2 divisors, whose sum is σ = 638155551890. Its totient is φ = 638155551888.

The previous prime is 638155551829. The next prime is 638155551899. The reversal of 638155551889 is 988155551836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 362383532289 + 275772019600 = 601983^2 + 525140^2 .

It is a cyclic number.

It is not a de Polignac number, because 638155551889 - 2¹⁵ = 638155519121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638155551889.

It is not a weakly prime, because it can be changed into another prime (638155551829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319077775944 + 319077775945.

It is an arithmetic number, because the mean of its divisors is an integer number (319077775945).

Almost surely, 2^638155551889 is an apocalyptic number.

It is an amenable number.

638155551889 is a deficient number, since it is larger than the sum of its proper divisors (1).

638155551889 is an equidigital number, since it uses as much as digits as its factorization.

638155551889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840000, while the sum is 64.

The spelling of 638155551889 in words is "six hundred thirty-eight billion, one hundred fifty-five million, five hundred fifty-one thousand, eight hundred eighty-nine".