133228728 has 96 divisors (see below), whose sum is σ = 386661600. Its totient is φ = 41293824.

The previous prime is 133228727. The next prime is 133228751. The reversal of 133228728 is 827822331.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 133228692 and 133228701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (133228727) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 108325 + ... + 109547.

It is an arithmetic number, because the mean of its divisors is an integer number (4027725).

Almost surely, 2^133228728 is an apocalyptic number.

133228728 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 133228728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (193330800).

133228728 is an abundant number, since it is smaller than the sum of its proper divisors (253432872).

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

133228728 is a wasteful number, since it uses less digits than its factorization.

133228728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1341 (or 1334 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 133228728 is about 11542.4749512399. The cubic root of 133228728 is about 510.7393198862.

It can be divided in two parts, 133228 and 728, that added together give a square (133956 = 366²).

The spelling of 133228728 in words is "one hundred thirty-three million, two hundred twenty-eight thousand, seven hundred twenty-eight".