128638818 has 72 divisors (see below), whose sum is σ = 353723760. Its totient is φ = 33410160.

The previous prime is 128638817. The next prime is 128638831. The reversal of 128638818 is 818836821.

128638818 is a `hidden beast` number, since 1 + 2 + 8 + 638 + 8 + 1 + 8 = 666.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (128638817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3073 + ... + 16331.

It is an arithmetic number, because the mean of its divisors is an integer number (4912830).

Almost surely, 2^128638818 is an apocalyptic number.

128638818 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 128638818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (176861880).

128638818 is an abundant number, since it is smaller than the sum of its proper divisors (225084942).

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

128638818 is a wasteful number, since it uses less digits than its factorization.

128638818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13292 (or 13282 counting only the distinct ones).

The product of its digits is 147456, while the sum is 45.

The square root of 128638818 is about 11341.9053954792. The cubic root of 128638818 is about 504.8054251549.

It can be divided in two parts, 1286 and 38818, that added together give a palindrome (40104).

The spelling of 128638818 in words is "one hundred twenty-eight million, six hundred thirty-eight thousand, eight hundred eighteen".