543661 has 2 divisors, whose sum is σ = 543662. Its totient is φ = 543660.

The previous prime is 543659. The next prime is 543671. The reversal of 543661 is 166345.

543661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 447561 + 96100 = 669^2 + 310^2 .

It is a cyclic number.

It is not a de Polignac number, because 543661 - 2¹ = 543659 is a prime.

Together with 543659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (543601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 271830 + 271831.

It is an arithmetic number, because the mean of its divisors is an integer number (271831).

2⁵⁴³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

543661 is a deficient number, since it is larger than the sum of its proper divisors (1).

543661 is an equidigital number, since it uses as much as digits as its factorization.

543661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 25.

The square root of 543661 is about 737.3337100662. Note that the first 3 decimals coincide. The cubic root of 543661 is about 81.6161416389.

The spelling of 543661 in words is "five hundred forty-three thousand, six hundred sixty-one".