Arithmetic structure of the standard genetic code

This preprint reports arithmetic regularities in the standard genetic code. The analysis examines nucleon-count quantities — proton sums (P), neutron sums (N), total nucleon sums (T), and their difference (Δ = P − N) — across codon groups defined by the Rumer partition and by third-position chemical axes (Keto/Amino, Strong/Weak, Purine/Pyrimidine). It documents systematic divisibility relations, in particular by 37, together with cross-group equalities and modular symmetries. The complete data and code supporting this work — input and computed datasets, a reproducibility script, supplementary control scripts, a Monte Carlo analysis under a random-code null model, an independent verification script, and an interactive visualizer — are archived as a separate Zenodo record (DOI: 10.5281/zenodo.20360037) and developed at github.com/RuslanKhafizov/genetic-code-arithmetic. Version v6 completes the revision of the Results section and brings its structure, terminology, notation, and treatment of dependencies into a consistent form.