725665 has 4 divisors (see below), whose sum is σ = 870804. Its totient is φ = 580528.

The previous prime is 725663. The next prime is 725671. The reversal of 725665 is 566527.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566527 = 13 ⋅43579.

It can be written as a sum of positive squares in 2 ways, for example, as 197136 + 528529 = 444^2 + 727^2 .

It is a cyclic number.

It is not a de Polignac number, because 725665 - 2¹ = 725663 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 725665.

It is not an unprimeable number, because it can be changed into a prime (725663) 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, 72562 + ... + 72571.

It is an arithmetic number, because the mean of its divisors is an integer number (217701).

2⁷²⁵⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

725665 is a deficient number, since it is larger than the sum of its proper divisors (145139).

725665 is a wasteful number, since it uses less digits than its factorization.

725665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145138.

The product of its digits is 12600, while the sum is 31.

The square root of 725665 is about 851.8597302373. The cubic root of 725665 is about 89.8625473838.

The spelling of 725665 in words is "seven hundred twenty-five thousand, six hundred sixty-five".