This number is a prime.
NASA used the space shuttle to place the Hubble Space Telescope (HST) in orbit around Earth at an altitude of 613 kilometers. [Luhn]
6+1+3 = 10, corresponding to the Ten Commandments. 613 is the 13th prime number whose digits add up to 10. Note the 13 Jewish principles of belief. [Doneel]
There are exactly 613 precepts (or laws) within the five books of Moses. [Aaron]
Even though only 6 of the 13 volumes of his Arithmetica have survived, Diophantus was regarged as the "Father of Algebra." [Motz]
The 18th centered square number. Note that 18 = 6*1*3. [Post]
NGC 613 is a barred spiral galaxy in the southern constellation Sculptor. The sum of digits of 613 approximates its visual magnitude.
613 is a mathematical enigma in the bewildering story Number of the End by Jason Earls. "Bring the first digit back to get 136, it's triangular. Now bring the first digit of that back to get 361, it's a square."
6132 is the largest known square that divides a number of the form n!+1, which happens when n=229, another prime. [Noe]
The only 3-digit number p such that 3^p-R(p) is prime. [Loungrides]
Smallest prime in the first prime triple whose the terms remain prime when each digit is replaced by its cube: (613, 216127), (617, 2161343), (619, 2161729). [Loungrides]
The smallest prime in a set of eleven consecutive primes such that deleting the first digit we find another set of eleven distinct primes. [Loungrides]
The only 3-digit prime formed from the index of a prime p followed by p, i.e., the 6th prime is 13. [Loungrides]
The B-F bond energy is close to 613 kJ/mol. [Yoder]