163661 has 2 divisors, whose sum is σ = 163662. Its totient is φ = 163660.

The previous prime is 163643. The next prime is 163673. The reversal of 163661 is 166361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 126025 + 37636 = 355^2 + 194^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-163661 is a prime.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 163661.

It is not a weakly prime, because it can be changed into another prime (163601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81830 + 81831.

It is an arithmetic number, because the mean of its divisors is an integer number (81831).

2¹⁶³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

163661 is a deficient number, since it is larger than the sum of its proper divisors (1).

163661 is an equidigital number, since it uses as much as digits as its factorization.

163661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 23.

The square root of 163661 is about 404.5503676923. The cubic root of 163661 is about 54.6992955781.

The spelling of 163661 in words is "one hundred sixty-three thousand, six hundred sixty-one".