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13681 is a prime number
BaseRepresentation
bin11010101110001
3200202201
43111301
5414211
6143201
754613
oct32561
920681
1013681
11a308
127b01
1362c5
144db3
1540c1
hex3571

13681 has 2 divisors, whose sum is σ = 13682. Its totient is φ = 13680.

The previous prime is 13679. The next prime is 13687. The reversal of 13681 is 18631.

13681 = T94 + T95 + T96.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13456 + 225 = 116^2 + 15^2 .

It is a cyclic number.

It is not a de Polignac number, because 13681 - 21 = 13679 is a prime.

It is a super-2 number, since 2×136812 = 374339522, which contains 22 as substring.

Together with 13679, it forms a pair of twin primes.

It is a Chen prime.

13681 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (13687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6840 + 6841.

It is an arithmetic number, because the mean of its divisors is an integer number (6841).

213681 is an apocalyptic number.

13681 is the 96-th centered triangular number.

It is an amenable number.

13681 is a deficient number, since it is larger than the sum of its proper divisors (1).

13681 is an equidigital number, since it uses as much as digits as its factorization.

13681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 144, while the sum is 19.

The square root of 13681 is about 116.9658069694. The cubic root of 13681 is about 23.9169583721.

Subtracting 13681 from its reverse (18631), we obtain a triangular number (4950 = T99).

It can be divided in two parts, 1368 and 1, that added together give a square (1369 = 372).

The spelling of 13681 in words is "thirteen thousand, six hundred eighty-one".