728921 has 2 divisors, whose sum is σ = 728922. Its totient is φ = 728920.

The previous prime is 728911. The next prime is 728927. The reversal of 728921 is 129827.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 577600 + 151321 = 760^2 + 389^2 .

It is a cyclic number.

It is not a de Polignac number, because 728921 - 2¹⁸ = 466777 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 728921.

It is not a weakly prime, because it can be changed into another prime (728927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364460 + 364461.

It is an arithmetic number, because the mean of its divisors is an integer number (364461).

2⁷²⁸⁹²¹ is an apocalyptic number.

It is an amenable number.

728921 is a deficient number, since it is larger than the sum of its proper divisors (1).

728921 is an equidigital number, since it uses as much as digits as its factorization.

728921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 29.

The square root of 728921 is about 853.7687040411. The cubic root of 728921 is about 89.9967488538.

The spelling of 728921 in words is "seven hundred twenty-eight thousand, nine hundred twenty-one".