Sixty

Sixty is the natural number that comes after fifty-nine and before sixty-one. In decimal notation, it is written as 60.

The word sixty comes from Old English sixti, formed with six plus the suffix -ty, historically denoting a group of ten. Cognates include German sechzig and Dutch zestig.

Sixty is an even composite number with prime factorization 2^2 × 3 × 5 and twelve positive divisors. It is often cited as a highly composite number for its size, reflecting a high count of divisors relative to smaller integers.

The ancient Mesopotamians used a sexagesimal, or base-60, numeral system. In modern use, 60 remains the basis for many time and angle measurements: there are 60 seconds in a minute, 60 minutes in an hour, and a full circle comprises 360 degrees (6 × 60), with degrees subdivided into minutes and seconds.

The number also appears in cultural and scientific contexts. In East Asia, the sexagenary cycle combines ten heavenly stems and twelve earthly branches to form a 60-year cycle. In chemistry, the element with atomic number 60 is neodymium (Nd).