126509 has 4 divisors (see below), whose sum is σ = 128316. Its totient is φ = 124704.

The previous prime is 126499. The next prime is 126517. The reversal of 126509 is 905621.

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 64009 + 62500 = 253^2 + 250^2 .

It is a cyclic number.

It is not a de Polignac number, because 126509 - 2⁴ = 126493 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 (122509) 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, 794 + ... + 939.

It is an arithmetic number, because the mean of its divisors is an integer number (32079).

2¹²⁶⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

126509 is a deficient number, since it is larger than the sum of its proper divisors (1807).

126509 is an equidigital number, since it uses as much as digits as its factorization.

126509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1806.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 126509 is about 355.6810368856. The cubic root of 126509 is about 50.2003957578.

The spelling of 126509 in words is "one hundred twenty-six thousand, five hundred nine".