125809 has 4 divisors (see below), whose sum is σ = 127204. Its totient is φ = 124416.

The previous prime is 125803. The next prime is 125813. The reversal of 125809 is 908521.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 102400 + 23409 = 320^2 + 153^2 .

It is a 5-Lehmer number, since φ(125809) divides (125809-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 125809 - 2⁵ = 125777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (125803) by changing a digit.

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

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 552 + ... + 745.

It is an arithmetic number, because the mean of its divisors is an integer number (31801).

2¹²⁵⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

125809 is a deficient number, since it is larger than the sum of its proper divisors (1395).

125809 is an equidigital number, since it uses as much as digits as its factorization.

125809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1394.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 125809 is about 354.6956441796. The cubic root of 125809 is about 50.1076347954.

The spelling of 125809 in words is "one hundred twenty-five thousand, eight hundred nine".