131878781 has 2 divisors, whose sum is σ = 131878782. Its totient is φ = 131878780.

The previous prime is 131878777. The next prime is 131878801. The reversal of 131878781 is 187878131.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67798756 + 64080025 = 8234^2 + 8005^2 .

It is a cyclic number.

It is not a de Polignac number, because 131878781 - 2² = 131878777 is a prime.

It is a super-2 number, since 2×131878781² = 34784025756091922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131878751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65939390 + 65939391.

It is an arithmetic number, because the mean of its divisors is an integer number (65939391).

Almost surely, 2^131878781 is an apocalyptic number.

It is an amenable number.

131878781 is a deficient number, since it is larger than the sum of its proper divisors (1).

131878781 is an equidigital number, since it uses as much as digits as its factorization.

131878781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 75264, while the sum is 44.

The square root of 131878781 is about 11483.8487015460. The cubic root of 131878781 is about 509.0084296565.

The spelling of 131878781 in words is "one hundred thirty-one million, eight hundred seventy-eight thousand, seven hundred eighty-one".