135989993 has 4 divisors (see below), whose sum is σ = 136125780. Its totient is φ = 135854208.

The previous prime is 135989983. The next prime is 135990013. The reversal of 135989993 is 399989531.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 399989531 = 67 ⋅5969993.

It can be written as a sum of positive squares in 2 ways, for example, as 56370064 + 79619929 = 7508^2 + 8923^2 .

It is a cyclic number.

It is not a de Polignac number, because 135989993 - 2¹⁰ = 135988969 is a prime.

It is a super-2 number, since 2×135989993² = 36986556392280098, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (135989983) 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, 66380 + ... + 68397.

It is an arithmetic number, because the mean of its divisors is an integer number (34031445).

Almost surely, 2^135989993 is an apocalyptic number.

It is an amenable number.

135989993 is a deficient number, since it is larger than the sum of its proper divisors (135787).

135989993 is a wasteful number, since it uses less digits than its factorization.

135989993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135786.

The product of its digits is 2361960, while the sum is 56.

The square root of 135989993 is about 11661.4747352125. The cubic root of 135989993 is about 514.2437046777.

The spelling of 135989993 in words is "one hundred thirty-five million, nine hundred eighty-nine thousand, nine hundred ninety-three".