13513781 has 4 divisors (see below), whose sum is σ = 13768812. Its totient is φ = 13258752.

The previous prime is 13513771. The next prime is 13513789. The reversal of 13513781 is 18731531.

13513781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 12013156 + 1500625 = 3466^2 + 1225^2 .

It is a cyclic number.

It is not a de Polignac number, because 13513781 - 2¹⁰ = 13512757 is a prime.

It is a super-2 number, since 2×13513781² = 365244553831922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13513789) 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, 127436 + ... + 127541.

It is an arithmetic number, because the mean of its divisors is an integer number (3442203).

Almost surely, 2^13513781 is an apocalyptic number.

It is an amenable number.

13513781 is a deficient number, since it is larger than the sum of its proper divisors (255031).

13513781 is an equidigital number, since it uses as much as digits as its factorization.

13513781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255030.

The product of its digits is 2520, while the sum is 29.

The square root of 13513781 is about 3676.1094923846. The cubic root of 13513781 is about 238.1911523669.

The spelling of 13513781 in words is "thirteen million, five hundred thirteen thousand, seven hundred eighty-one".