725440321 has 4 divisors (see below), whose sum is σ = 725505732. Its totient is φ = 725374912.

The previous prime is 725440319. The next prime is 725440327. The reversal of 725440321 is 123044527.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 123044527 = 907 ⋅135661.

It can be written as a sum of positive squares in 2 ways, for example, as 151167025 + 574273296 = 12295^2 + 23964^2 .

It is a cyclic number.

It is not a de Polignac number, because 725440321 - 2¹ = 725440319 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 725440321.

It is not an unprimeable number, because it can be changed into a prime (725440327) 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, 11476 + ... + 39781.

It is an arithmetic number, because the mean of its divisors is an integer number (181376433).

Almost surely, 2^725440321 is an apocalyptic number.

It is an amenable number.

725440321 is a deficient number, since it is larger than the sum of its proper divisors (65411).

725440321 is a wasteful number, since it uses less digits than its factorization.

725440321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65410.

The product of its (nonzero) digits is 6720, while the sum is 28.

The square root of 725440321 is about 26933.9993502636. Note that the first 3 decimals coincide. The cubic root of 725440321 is about 898.5327207020.

Adding to 725440321 its reverse (123044527), we get a palindrome (848484848).

The spelling of 725440321 in words is "seven hundred twenty-five million, four hundred forty thousand, three hundred twenty-one".