728521 has 2 divisors, whose sum is σ = 728522. Its totient is φ = 728520.

The previous prime is 728489. The next prime is 728527. The reversal of 728521 is 125827.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 436921 + 291600 = 661^2 + 540^2 .

It is a cyclic number.

It is not a de Polignac number, because 728521 - 2⁵ = 728489 is a prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (728527) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364260 + 364261.

It is an arithmetic number, because the mean of its divisors is an integer number (364261).

2⁷²⁸⁵²¹ is an apocalyptic number.

It is an amenable number.

728521 is a deficient number, since it is larger than the sum of its proper divisors (1).

728521 is an equidigital number, since it uses as much as digits as its factorization.

728521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1120, while the sum is 25.

The square root of 728521 is about 853.5344164121. The cubic root of 728521 is about 89.9802837469.

The spelling of 728521 in words is "seven hundred twenty-eight thousand, five hundred twenty-one".