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131687681 = 641205441
BaseRepresentation
bin1111101100101…
…10010100000001
3100011210102112112
413312112110001
5232203001211
621022305105
73156220046
oct766262401
9304712475
10131687681
11683749a4
1238128195
1321389a08
14136bd1cd
15b86388b
hex7d96501

131687681 has 4 divisors (see below), whose sum is σ = 131893764. Its totient is φ = 131481600.

The previous prime is 131687671. The next prime is 131687687. The reversal of 131687681 is 186786131.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 45495025 + 86192656 = 6745^2 + 9284^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-131687681 is a prime.

It is a super-2 number, since 2×1316876812 = 34683290654315522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (131687687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102080 + ... + 103361.

It is an arithmetic number, because the mean of its divisors is an integer number (32973441).

It is the magic constant of a 641 × 641 magic square.

Almost surely, 2131687681 is an apocalyptic number.

It is an amenable number.

131687681 is a deficient number, since it is larger than the sum of its proper divisors (206083).

131687681 is an equidigital number, since it uses as much as digits as its factorization.

131687681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206082.

The product of its digits is 48384, while the sum is 41.

The square root of 131687681 is about 11475.5253038804. The cubic root of 131687681 is about 508.7624498963.

The spelling of 131687681 in words is "one hundred thirty-one million, six hundred eighty-seven thousand, six hundred eighty-one".

Divisors: 1 641 205441 131687681