12721728 has 56 divisors (see below), whose sum is σ = 33942528. Its totient is φ = 4205056.

The previous prime is 12721721. The next prime is 12721739. The reversal of 12721728 is 82712721.

It is a happy number.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 12721695 and 12721704.

It is not an unprimeable number, because it can be changed into a prime (12721721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33025 + ... + 33407.

Almost surely, 2^12721728 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 12721728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16971264).

12721728 is an abundant number, since it is smaller than the sum of its proper divisors (21220800).

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

12721728 is a wasteful number, since it uses less digits than its factorization.

12721728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 571 (or 561 counting only the distinct ones).

The product of its digits is 3136, while the sum is 30.

The square root of 12721728 is about 3566.7531453690. The cubic root of 12721728 is about 233.4436340186.

The spelling of 12721728 in words is "twelve million, seven hundred twenty-one thousand, seven hundred twenty-eight".