133531 has 4 divisors (see below), whose sum is σ = 135592. Its totient is φ = 131472.

The previous prime is 133519. The next prime is 133541. The reversal of 133531 is 135331.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 135331 = 7 ⋅19333.

It is a cyclic number.

It is not a de Polignac number, because 133531 - 2⁵ = 133499 is a prime.

It is a super-2 number, since 2×133531² = 35661055922, which contains 22 as substring.

It is a Duffinian number.

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, 930 + ... + 1063.

It is an arithmetic number, because the mean of its divisors is an integer number (33898).

2¹³³⁵³¹ is an apocalyptic number.

133531 is a deficient number, since it is larger than the sum of its proper divisors (2061).

133531 is an equidigital number, since it uses as much as digits as its factorization.

133531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2060.

The product of its digits is 135, while the sum is 16.

The square root of 133531 is about 365.4189376592. The cubic root of 133531 is about 51.1125286661.

Adding to 133531 its reverse (135331), we get a palindrome (268862).

The spelling of 133531 in words is "one hundred thirty-three thousand, five hundred thirty-one".