1781128728 has 48 divisors (see below), whose sum is σ = 4990237200. Its totient is φ = 573236160.

The previous prime is 1781128711. The next prime is 1781128747. The reversal of 1781128728 is 8278211871.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 424428 + ... + 428603.

It is an arithmetic number, because the mean of its divisors is an integer number (103963275).

Almost surely, 2^1781128728 is an apocalyptic number.

1781128728 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1781128728 is an abundant number, since it is smaller than the sum of its proper divisors (3209108472).

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

1781128728 is a wasteful number, since it uses less digits than its factorization.

1781128728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 853072 (or 853065 counting only the distinct ones).

The product of its digits is 100352, while the sum is 45.

The square root of 1781128728 is about 42203.4208092188. The cubic root of 1781128728 is about 1212.1743859131.

The spelling of 1781128728 in words is "one billion, seven hundred eighty-one million, one hundred twenty-eight thousand, seven hundred twenty-eight".