55661 has 2 divisors, whose sum is σ = 55662. Its totient is φ = 55660.
The previous prime is 55639. The next prime is 55663. The reversal of 55661 is 16655.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 42436 + 13225 = 206^2 + 115^2 .
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-55661 is a prime.
It is a Sophie Germain prime.
Together with 55663, it forms a pair of twin primes.
It is a Chen prime.
It is a Curzon number.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (55663) by changing a digit.
It is a good prime.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27830 + 27831.
It is an arithmetic number, because the mean of its divisors is an integer number (27831).
255661 is an apocalyptic number.
It is an amenable number.
55661 is a deficient number, since it is larger than the sum of its proper divisors (1).
55661 is an equidigital number, since it uses as much as digits as its factorization.
55661 is an evil number, because the sum of its binary digits is even.
The product of its digits is 900, while the sum is 23.
The square root of 55661 is about 235.9258358044. The cubic root of 55661 is about 38.1812669130.
The spelling of 55661 in words is "fifty-five thousand, six hundred sixty-one".
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