Search a number
BaseRepresentation
bin100000000111111101
320200111101
4200013331
513202311
62453101
71055422
oct400775
9220441
10131581
118a94a
1264191
1347b78
1435d49
1528ec1
hex201fd

131581 has 2 divisors, whose sum is σ = 131582. Its totient is φ = 131580.

The previous prime is 131561. The next prime is 131591. The reversal of 131581 is 185131.

131581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 95481 + 36100 = 309^2 + 190^2 .

It is an emirp because it is prime and its reverse (185131) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 131581 - 211 = 129533 is a prime.

It is a super-2 number, since 2×1315812 = 34627119122, which contains 22 as substring.

It is a congruent number.

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

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65790 + 65791.

It is an arithmetic number, because the mean of its divisors is an integer number (65791).

2131581 is an apocalyptic number.

It is an amenable number.

131581 is a deficient number, since it is larger than the sum of its proper divisors (1).

131581 is an equidigital number, since it uses as much as digits as its factorization.

131581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120, while the sum is 19.

The square root of 131581 is about 362.7409544013. The cubic root of 131581 is about 50.8625028918.

The spelling of 131581 in words is "one hundred thirty-one thousand, five hundred eighty-one".