725721 has 4 divisors (see below), whose sum is σ = 967632. Its totient is φ = 483812.

The previous prime is 725687. The next prime is 725723. The reversal of 725721 is 127527.

725721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 127527 = 3 ⋅42509.

It is a cyclic number.

It is not a de Polignac number, because 725721 - 2⁹ = 725209 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 725691 and 725700.

It is not an unprimeable number, because it can be changed into a prime (725723) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120951 + ... + 120956.

It is an arithmetic number, because the mean of its divisors is an integer number (241908).

2⁷²⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

725721 is a deficient number, since it is larger than the sum of its proper divisors (241911).

725721 is a wasteful number, since it uses less digits than its factorization.

725721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241910.

The product of its digits is 980, while the sum is 24.

The square root of 725721 is about 851.8925988644. The cubic root of 725721 is about 89.8648589065.

The spelling of 725721 in words is "seven hundred twenty-five thousand, seven hundred twenty-one".