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13957 = 17821

13957 has 4 divisors (see below), whose sum is σ = 14796. Its totient is φ = 13120.

The previous prime is 13933. The next prime is 13963. The reversal of 13957 is 75931.

13957 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

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 7396 + 6561 = 86^2 + 81^2 .

It is a cyclic number.

It is not a de Polignac number, because 13957 - 27 = 13829 is a prime.

It is a Duffinian number.

13957 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13907) 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 in 3 ways as a sum of consecutive naturals, for example, 394 + ... + 427.

It is an arithmetic number, because the mean of its divisors is an integer number (3699).

213957 is an apocalyptic number.

13957 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

13957 is a deficient number, since it is larger than the sum of its proper divisors (839).

13957 is an equidigital number, since it uses as much as digits as its factorization.

13957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 838.

The product of its digits is 945, while the sum is 25.

The square root of 13957 is about 118.1397477566. The cubic root of 13957 is about 24.0767220697.

It can be divided in two parts, 139 and 57, that added together give a square (196 = 142).

The spelling of 13957 in words is "thirteen thousand, nine hundred fifty-seven".

Divisors: 1 17 821 13957