135218231 has 4 divisors (see below), whose sum is σ = 142335000. Its totient is φ = 128101464.

The previous prime is 135218207. The next prime is 135218257. The reversal of 135218231 is 132812531.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 132812531 = 7411 ⋅17921.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-135218231 is a prime.

It is a super-2 number, since 2×135218231² = 36567939989538722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 135218231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (135218131) 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, 3558356 + ... + 3558393.

It is an arithmetic number, because the mean of its divisors is an integer number (35583750).

Almost surely, 2^135218231 is an apocalyptic number.

135218231 is a deficient number, since it is larger than the sum of its proper divisors (7116769).

135218231 is an equidigital number, since it uses as much as digits as its factorization.

135218231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7116768.

The product of its digits is 1440, while the sum is 26.

The square root of 135218231 is about 11628.3374134052. The cubic root of 135218231 is about 513.2690572339.

The spelling of 135218231 in words is "one hundred thirty-five million, two hundred eighteen thousand, two hundred thirty-one".