728138 has 4 divisors (see below), whose sum is σ = 1092210. Its totient is φ = 364068.

The previous prime is 728131. The next prime is 728173. The reversal of 728138 is 831827.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 727609 + 529 = 853^2 + 23^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 728138.

It is not an unprimeable number, because it can be changed into a prime (728131) by changing a digit.

728138 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 182033 + ... + 182036.

2⁷²⁸¹³⁸ is an apocalyptic number.

728138 is a deficient number, since it is larger than the sum of its proper divisors (364072).

728138 is a wasteful number, since it uses less digits than its factorization.

728138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364071.

The product of its digits is 2688, while the sum is 29.

The square root of 728138 is about 853.3100257234. The cubic root of 728138 is about 89.9645127581.

The spelling of 728138 in words is "seven hundred twenty-eight thousand, one hundred thirty-eight".