135721013 has 4 divisors (see below), whose sum is σ = 143704620. Its totient is φ = 127737408.

The previous prime is 135720997. The next prime is 135721031. The reversal of 135721013 is 310127531.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 80694289 + 55026724 = 8983^2 + 7418^2 .

It is a cyclic number.

It is not a de Polignac number, because 135721013 - 2⁴ = 135720997 is a prime.

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 135721013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (135721043) 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, 3991778 + ... + 3991811.

It is an arithmetic number, because the mean of its divisors is an integer number (35926155).

Almost surely, 2^135721013 is an apocalyptic number.

It is an amenable number.

135721013 is a deficient number, since it is larger than the sum of its proper divisors (7983607).

135721013 is an equidigital number, since it uses as much as digits as its factorization.

135721013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7983606.

The product of its (nonzero) digits is 630, while the sum is 23.

The square root of 135721013 is about 11649.9361800827. The cubic root of 135721013 is about 513.9044332210.

Adding to 135721013 its reverse (310127531), we get a palindrome (445848544).

The spelling of 135721013 in words is "one hundred thirty-five million, seven hundred twenty-one thousand, thirteen".