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BaseRepresentation
bin100000000111101001
320200110122
4200013221
513202221
62453025
71055363
oct400751
9220418
10131561
118a931
1264175
1347b61
1435d33
1528eab
hex201e9

131561 has 2 divisors, whose sum is σ = 131562. Its totient is φ = 131560.

The previous prime is 131543. The next prime is 131581. The reversal of 131561 is 165131.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 118336 + 13225 = 344^2 + 115^2 .

It is a cyclic number.

It is not a de Polignac number, because 131561 - 26 = 131497 is a prime.

It is not a weakly prime, because it can be changed into another prime (131501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65780 + 65781.

It is an arithmetic number, because the mean of its divisors is an integer number (65781).

2131561 is an apocalyptic number.

It is an amenable number.

131561 is a deficient number, since it is larger than the sum of its proper divisors (1).

131561 is an equidigital number, since it uses as much as digits as its factorization.

131561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90, while the sum is 17.

The square root of 131561 is about 362.7133854712. The cubic root of 131561 is about 50.8599257680.

Adding to 131561 its reverse (165131), we get a palindrome (296692).

The spelling of 131561 in words is "one hundred thirty-one thousand, five hundred sixty-one".