43721728 has 22 divisors (see below), whose sum is σ = 87402806. Its totient is φ = 21860352.

The previous prime is 43721723. The next prime is 43721731. The reversal of 43721728 is 82712734.

It can be written as a sum of positive squares in only one way, i.e., 29942784 + 13778944 = 5472^2 + 3712^2 .

It is a junction number, because it is equal to n+sod(n) for n = 43721693 and 43721702.

It is not an unprimeable number, because it can be changed into a prime (43721723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20325 + ... + 22372.

Almost surely, 2^43721728 is an apocalyptic number.

It is an amenable number.

43721728 is a deficient number, since it is larger than the sum of its proper divisors (43681078).

43721728 is an equidigital number, since it uses as much as digits as its factorization.

43721728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42717 (or 42699 counting only the distinct ones).

The product of its digits is 18816, while the sum is 34.

The square root of 43721728 is about 6612.2407699660. The cubic root of 43721728 is about 352.2890188269.

The spelling of 43721728 in words is "forty-three million, seven hundred twenty-one thousand, seven hundred twenty-eight".