133 can be written using four 4's:
See also 113
133 has 4
divisors (see below), whose sum is σ = 160
Its totient is φ = 108
The previous prime is 131. The next prime is 137. The reversal of 133 is 331.
It is a happy number.
133 is nontrivially palindromic in base 11.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.
It is a sliding number, since 133 = 8 + 125 and 1/8 + 1/125 = 0.133.
It is a 3-Lehmer number, since φ(133) divides (133-1)3.
It is a cyclic number.
It is not a de Polignac number, because 133 - 21 = 131 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (7), and also a Moran number because the ratio is a prime number: 19 = 133 / (1 + 3 + 3).
133 is an idoneal number.
It is the 12-th Hogben number.
It is a Duffinian number.
133 is a modest number, since divided by 33 gives 1 as remainder.
133 is a lucky number.
133 is a nontrivial repdigit in base 11.
It is a plaindrome in base 9, base 10, base 11 and base 15.
It is a nialpdrome in base 11, base 12, base 13, base 14 and base 16.
It is a zygodrome in base 11.
It is a congruent number.
It is a nontrivial repunit in base 11.
It is a pernicious number, because its binary representation contains a prime number (3) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3 + ... + 16.
It is an arithmetic number, because the mean of its divisors is an integer number (40).
133 is the 7-th octagonal number.
It is an amenable number.
133 is a deficient number, since it is larger than the sum of its proper divisors (27).
133 is an equidigital number, since it uses as much as digits as its factorization.
133 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 26.
The product of its digits is 9, while the sum is 7.
The square root of 133 is about 11.5325625947.
The cubic root of 133 is about 5.1044687220.
Adding to 133 its reverse (331), we get a palindrome (464).
It can be divided in two parts, 13 and 3, that added together give a 4-th power (16 = 24).
The spelling of 133 in words is "one hundred thirty-three", and thus it is an aban number.