131609 has 4 divisors (see below), whose sum is σ = 135204. Its totient is φ = 128016.

The previous prime is 131591. The next prime is 131611. The reversal of 131609 is 906131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 906131 = 23 ⋅39397.

It can be written as a sum of positive squares in 2 ways, for example, as 67600 + 64009 = 260^2 + 253^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (131639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1742 + ... + 1815.

It is an arithmetic number, because the mean of its divisors is an integer number (33801).

2¹³¹⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

131609 is a deficient number, since it is larger than the sum of its proper divisors (3595).

131609 is an equidigital number, since it uses as much as digits as its factorization.

131609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3594.

The product of its (nonzero) digits is 162, while the sum is 20.

The square root of 131609 is about 362.7795473838. The cubic root of 131609 is about 50.8661104265.

The spelling of 131609 in words is "one hundred thirty-one thousand, six hundred nine".