1005721728 has 128 divisors (see below), whose sum is σ = 2926290240. Its totient is φ = 303513600.

The previous prime is 1005721727. The next prime is 1005721733. The reversal of 1005721728 is 8271275001.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×1005721728² = 2022952388342611968, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (1005721727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1930108 + ... + 1930628.

Almost surely, 2^1005721728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1005721728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1463145120).

1005721728 is an abundant number, since it is smaller than the sum of its proper divisors (1920568512).

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

1005721728 is a wasteful number, since it uses less digits than its factorization.

1005721728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1006 (or 994 counting only the distinct ones).

The product of its (nonzero) digits is 7840, while the sum is 33.

The square root of 1005721728 is about 31713.1160247617. The cubic root of 1005721728 is about 1001.9036166111.

Adding to 1005721728 its reverse (8271275001), we get a palindrome (9276996729).

The spelling of 1005721728 in words is "one billion, five million, seven hundred twenty-one thousand, seven hundred twenty-eight".