57

57 is a natural number that comes after 56 and before 58. It is written LVII in Roman numerals, and in binary, hexadecimal, and octal it is 111001, 0x39, and 71 respectively.

In mathematics, 57 is an odd composite number with prime factorization 3 × 19, making it a semiprime. Its divisors are 1, 3, 19, and 57. The sum of all divisors is 80, so the sum of proper divisors is 23, rendering 57 a deficient number. It can be expressed as the sum of two consecutive integers (28 + 29) and also as the sum of three consecutive integers (18 + 19 + 20).

57 is the atomic number of lanthanum (La), a soft, silvery-white metal in the lanthanide series. Lanthanum is used in various applications, including catalysts and batteries, and it serves as a key component in certain high-clarity glass and lighting materials.

The international dialing code +57 is assigned to Colombia. In cultural and historical contexts, 1957 is a common reference point for events in the mid-20th century, but no single global standard is tied to the number 57 beyond such uses.