131921 has 4 divisors (see below), whose sum is σ = 136500. Its totient is φ = 127344.

The previous prime is 131909. The next prime is 131927. The reversal of 131921 is 129131.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129131 = 139 ⋅929.

It can be written as a sum of positive squares in 2 ways, for example, as 83521 + 48400 = 289^2 + 220^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131921 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 131921.

It is not an unprimeable number, because it can be changed into a prime (131927) 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, 2246 + ... + 2303.

It is an arithmetic number, because the mean of its divisors is an integer number (34125).

2¹³¹⁹²¹ is an apocalyptic number.

It is an amenable number.

131921 is a deficient number, since it is larger than the sum of its proper divisors (4579).

131921 is an equidigital number, since it uses as much as digits as its factorization.

131921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4578.

The product of its digits is 54, while the sum is 17.

The square root of 131921 is about 363.2093060482. The cubic root of 131921 is about 50.9062740982.

The spelling of 131921 in words is "one hundred thirty-one thousand, nine hundred twenty-one".