725173621 has 4 divisors (see below), whose sum is σ = 731826700. Its totient is φ = 718520544.

The previous prime is 725173597. The next prime is 725173639. The reversal of 725173621 is 126371527.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 126371527 = 19 ⋅6651133.

It can be written as a sum of positive squares in 2 ways, for example, as 175271121 + 549902500 = 13239^2 + 23450^2 .

It is a cyclic number.

It is not a de Polignac number, because 725173621 - 2¹⁹ = 724649333 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (725173651) 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, 3326376 + ... + 3326593.

It is an arithmetic number, because the mean of its divisors is an integer number (182956675).

Almost surely, 2^725173621 is an apocalyptic number.

It is an amenable number.

725173621 is a deficient number, since it is larger than the sum of its proper divisors (6653079).

725173621 is a wasteful number, since it uses less digits than its factorization.

725173621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6653078.

The product of its digits is 17640, while the sum is 34.

The square root of 725173621 is about 26929.0479037043. The cubic root of 725173621 is about 898.4225953788.

The spelling of 725173621 in words is "seven hundred twenty-five million, one hundred seventy-three thousand, six hundred twenty-one".