131105561 has 2 divisors, whose sum is σ = 131105562. Its totient is φ = 131105560.

The previous prime is 131105539. The next prime is 131105563. The reversal of 131105561 is 165501131.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 94575625 + 36529936 = 9725^2 + 6044^2 .

It is a cyclic number.

It is not a de Polignac number, because 131105561 - 2¹⁰ = 131104537 is a prime.

Together with 131105563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (131105563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65552780 + 65552781.

It is an arithmetic number, because the mean of its divisors is an integer number (65552781).

Almost surely, 2^131105561 is an apocalyptic number.

It is an amenable number.

131105561 is a deficient number, since it is larger than the sum of its proper divisors (1).

131105561 is an equidigital number, since it uses as much as digits as its factorization.

131105561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 450, while the sum is 23.

The square root of 131105561 is about 11450.1336673421. The cubic root of 131105561 is about 508.0116880461.

Adding to 131105561 its reverse (165501131), we get a palindrome (296606692).

The spelling of 131105561 in words is "one hundred thirty-one million, one hundred five thousand, five hundred sixty-one".