133981609 has 4 divisors (see below), whose sum is σ = 134008660. Its totient is φ = 133954560.

The previous prime is 133981591. The next prime is 133981619. The reversal of 133981609 is 906189331.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 906189331 = 11239 ⋅80629.

It can be written as a sum of positive squares in 2 ways, for example, as 44622400 + 89359209 = 6680^2 + 9453^2 .

It is a cyclic number.

It is not a de Polignac number, because 133981609 - 2⁵ = 133981577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (133981619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3732 + ... + 16789.

It is an arithmetic number, because the mean of its divisors is an integer number (33502165).

Almost surely, 2^133981609 is an apocalyptic number.

It is an amenable number.

133981609 is a deficient number, since it is larger than the sum of its proper divisors (27051).

133981609 is an equidigital number, since it uses as much as digits as its factorization.

133981609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27050.

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 133981609 is about 11575.0425053215. The cubic root of 133981609 is about 511.6995829296.

The spelling of 133981609 in words is "one hundred thirty-three million, nine hundred eighty-one thousand, six hundred nine".