133521 has 4 divisors (see below), whose sum is σ = 178032. Its totient is φ = 89012.

The previous prime is 133519. The next prime is 133541. The reversal of 133521 is 125331.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 125331 = 3 ⋅41777.

It is a cyclic number.

It is not a de Polignac number, because 133521 - 2¹ = 133519 is a prime.

It is a D-number.

133521 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 133521.

It is not an unprimeable number, because it can be changed into a prime (133541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22251 + ... + 22256.

It is an arithmetic number, because the mean of its divisors is an integer number (44508).

2¹³³⁵²¹ is an apocalyptic number.

It is an amenable number.

133521 is a deficient number, since it is larger than the sum of its proper divisors (44511).

133521 is an equidigital number, since it uses as much as digits as its factorization.

133521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44510.

The product of its digits is 90, while the sum is 15.

The square root of 133521 is about 365.4052544778. The cubic root of 133521 is about 51.1112527126. Note that the first 3 decimals are identical.

Adding to 133521 its reverse (125331), we get a palindrome (258852).

The spelling of 133521 in words is "one hundred thirty-three thousand, five hundred twenty-one".