131278321 has 4 divisors (see below), whose sum is σ = 131310144. Its totient is φ = 131246500.

The previous prime is 131278313. The next prime is 131278327. The reversal of 131278321 is 123872131.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 123872131 = 797 ⋅155423.

It is a cyclic number.

It is not a de Polignac number, because 131278321 - 2³ = 131278313 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 131278321.

It is not an unprimeable number, because it can be changed into a prime (131278327) 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, 8605 + ... + 18346.

It is an arithmetic number, because the mean of its divisors is an integer number (32827536).

Almost surely, 2^131278321 is an apocalyptic number.

It is an amenable number.

131278321 is a deficient number, since it is larger than the sum of its proper divisors (31823).

131278321 is an equidigital number, since it uses as much as digits as its factorization.

131278321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31822.

The product of its digits is 2016, while the sum is 28.

The square root of 131278321 is about 11457.6752004933. The cubic root of 131278321 is about 508.2347286183.

The spelling of 131278321 in words is "one hundred thirty-one million, two hundred seventy-eight thousand, three hundred twenty-one".