Number Properties Analyzer explains what a number actually is, all at once — handy for number-theory practice, cryptography basics, checking your own predicate functions while coding, or simply seeing how special a number is.

Properties checked:
· Prime — divisible only by 1 and itself (≥ 2), e.g. 2, 3, 5, 7, 11;
· Perfect square — the square of an integer, e.g. 0, 1, 4, 9, 16, 25;
· Fibonacci number — appears in the sequence 1, 1, 2, 3, 5, 8, 13 …;
· Happy number — repeatedly summing the squares of the digits eventually reaches 1, e.g. 1, 7, 10, 13, 19, 28;
· Parity and digit count are reported alongside.

Steps:
1. Paste the numbers; commas, spaces, newlines or any separator work;
2. Choose a filter: list everything / only primes / only perfect squares / only Fibonacci numbers / only happy numbers — to pull out just the matching ones;
3. Optionally tick Keep unique;
4. Set the separator to control how the text box output is laid out — one value per line by default;
5. Click Run. Results appear in the text box and in the table below.
Note: only integers are recognised; decimals are ignored. Negative numbers are not tested for these properties (all shown as No) and parity uses the absolute value. Primality uses Miller-Rabin — deterministic below 2^64 and a very high-probability answer beyond that — and every computation uses big integers, so values past JavaScript's safe integer limit (2^53-1) stay exact.