638889223128 has 64 divisors (see below), whose sum is σ = 1720369056000. Its totient is φ = 196548992640.

The previous prime is 638889223127. The next prime is 638889223129. The reversal of 638889223128 is 821322988836.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (638889223127) and next prime (638889223129).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638889223127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1768923 + ... + 2099253.

It is an arithmetic number, because the mean of its divisors is an integer number (26880766500).

Almost surely, 2^638889223128 is an apocalyptic number.

It is an amenable number.

638889223128 is an abundant number, since it is smaller than the sum of its proper divisors (1081479832872).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638889223128 is a wasteful number, since it uses less digits than its factorization.

638889223128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336552 (or 336548 counting only the distinct ones).

The product of its digits is 15925248, while the sum is 60.

The spelling of 638889223128 in words is "six hundred thirty-eight billion, eight hundred eighty-nine million, two hundred twenty-three thousand, one hundred twenty-eight".