135989 has 4 divisors (see below), whose sum is σ = 155424. Its totient is φ = 116556.

The previous prime is 135979. The next prime is 136013. The reversal of 135989 is 989531.

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: 989531 = 197 ⋅5023.

It is a cyclic number.

It is not a de Polignac number, because 135989 - 2¹² = 131893 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 (135929) 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, 9707 + ... + 9720.

It is an arithmetic number, because the mean of its divisors is an integer number (38856).

2¹³⁵⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

135989 is a deficient number, since it is larger than the sum of its proper divisors (19435).

135989 is an equidigital number, since it uses as much as digits as its factorization.

135989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19434.

The product of its digits is 9720, while the sum is 35.

The square root of 135989 is about 368.7668640212. The cubic root of 135989 is about 51.4242453004.

The spelling of 135989 in words is "one hundred thirty-five thousand, nine hundred eighty-nine".