133533661 has 4 divisors (see below), whose sum is σ = 138138300. Its totient is φ = 128929024.

The previous prime is 133533643. The next prime is 133533689. The reversal of 133533661 is 166335331.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166335331 = 1069 ⋅155599.

It can be written as a sum of positive squares in 2 ways, for example, as 32148900 + 101384761 = 5670^2 + 10069^2 .

It is a cyclic number.

It is not a de Polignac number, because 133533661 - 2⁹ = 133533149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (133533601) 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, 2302276 + ... + 2302333.

It is an arithmetic number, because the mean of its divisors is an integer number (34534575).

Almost surely, 2^133533661 is an apocalyptic number.

It is an amenable number.

133533661 is a deficient number, since it is larger than the sum of its proper divisors (4604639).

133533661 is an equidigital number, since it uses as much as digits as its factorization.

133533661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4604638.

The product of its digits is 14580, while the sum is 31.

The square root of 133533661 is about 11555.6765704133. The cubic root of 133533661 is about 511.1286818664.

Adding to 133533661 its reverse (166335331), we get a palindrome (299868992).

The spelling of 133533661 in words is "one hundred thirty-three million, five hundred thirty-three thousand, six hundred sixty-one".