126809 has 4 divisors (see below), whose sum is σ = 127716. Its totient is φ = 125904.

The previous prime is 126781. The next prime is 126823. The reversal of 126809 is 908621.

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: 908621 = 7 ⋅129803.

It can be written as a sum of positive squares in 2 ways, for example, as 120409 + 6400 = 347^2 + 80^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-126809 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126839) 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, 194 + ... + 539.

It is an arithmetic number, because the mean of its divisors is an integer number (31929).

2¹²⁶⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

126809 is a deficient number, since it is larger than the sum of its proper divisors (907).

126809 is an equidigital number, since it uses as much as digits as its factorization.

126809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 126809 is about 356.1025133301. The cubic root of 126809 is about 50.2400457168.

The spelling of 126809 in words is "one hundred twenty-six thousand, eight hundred nine".