131311781 has 2 divisors, whose sum is σ = 131311782. Its totient is φ = 131311780.

The previous prime is 131311769. The next prime is 131311783. The reversal of 131311781 is 187113131.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 126922756 + 4389025 = 11266^2 + 2095^2 .

It is a cyclic number.

It is not a de Polignac number, because 131311781 - 2¹⁰ = 131310757 is a prime.

It is a super-2 number, since 2×131311781² = 34485567658783922, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 131311783, it forms a pair of twin primes.

It is a Chen prime.

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 131311781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131311783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65655890 + 65655891.

It is an arithmetic number, because the mean of its divisors is an integer number (65655891).

Almost surely, 2^131311781 is an apocalyptic number.

It is an amenable number.

131311781 is a deficient number, since it is larger than the sum of its proper divisors (1).

131311781 is an equidigital number, since it uses as much as digits as its factorization.

131311781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504, while the sum is 26.

The square root of 131311781 is about 11459.1352640590. The cubic root of 131311781 is about 508.2779042909.

The spelling of 131311781 in words is "one hundred thirty-one million, three hundred eleven thousand, seven hundred eighty-one".