33

33 (thirty-three) is the natural number following 32 and preceding 34. In mathematics 33 is: specifically, the 8th distinct semiprime, it being the 3rd of the form (3.q) where q is a higher prime. It also contains a semiprime aliquot sum of 15, within an aliquot sequence of four members (33, 15, 9, 4, 3, 1, 0) in the prime 3-aliquot tree. the largest positive integer that cannot be expressed as a sum of different triangular numbers. It is also the largest of twelve integers that are not the sum of five non-zero squares. the smallest odd repdigit that is not a prime number. the sum of the first four positive factorials. the sum of the sum of the divisors of the first six positive integers. the sum of three cubes: equal to the sum of the squares of the digits of its own square in bases 9, 16 and 31. For numbers greater than 1, this is a rare property to have in more than one base. the first member of the first cluster of three semiprimes 33, 34, 35; the next such cluster is 85, 86, 87. It is also the smallest integer such that it and the next two integers all have the same number of divisors. the first double digit centered dodecahedral number. divisible by the number of prime numbers (11) below 33. a palindrome in both decimal and binary. A positive definite quadratic integer matrix represents all odd numbers when it contains at least the set of seven integers: {1, 3, 5, 7, 11, 15, 33}. In science The atomic number of arsenic. 33 is, according to the Newton scale, the temperature at which water boils. A normal human spine has, on average, 33 vertebrae when the bones that form the coccyx are counted individually.