1331785728 has 312 divisors, whose sum is σ = 4746586208. Its totient is φ = 350355456.

The previous prime is 1331785727. The next prime is 1331785757. The reversal of 1331785728 is 8275871331.

1331785728 is a `hidden beast` number, since 1 + 3 + 3 + 1 + 78 + 572 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (312).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1331785727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3354426 + ... + 3354822.

Almost surely, 2^1331785728 is an apocalyptic number.

1331785728 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 1331785728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2373293104).

1331785728 is an abundant number, since it is smaller than the sum of its proper divisors (3414800480).

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

1331785728 is a wasteful number, since it uses less digits than its factorization.

1331785728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447 (or 422 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The square root of 1331785728 is about 36493.6395554075. The cubic root of 1331785728 is about 1100.2164114154.

The spelling of 1331785728 in words is "one billion, three hundred thirty-one million, seven hundred eighty-five thousand, seven hundred twenty-eight".