13138781 has 2 divisors, whose sum is σ = 13138782. Its totient is φ = 13138780.

The previous prime is 13138771. The next prime is 13138789. The reversal of 13138781 is 18783131.

13138781 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10023556 + 3115225 = 3166^2 + 1765^2 .

It is a cyclic number.

It is not a de Polignac number, because 13138781 - 2¹⁰ = 13137757 is a prime.

It is a super-2 number, since 2×13138781² = 345255132331922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13138789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6569390 + 6569391.

It is an arithmetic number, because the mean of its divisors is an integer number (6569391).

Almost surely, 2^13138781 is an apocalyptic number.

It is an amenable number.

13138781 is a deficient number, since it is larger than the sum of its proper divisors (1).

13138781 is an equidigital number, since it uses as much as digits as its factorization.

13138781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 32.

The square root of 13138781 is about 3624.7456462489. The cubic root of 13138781 is about 235.9672282848.

The spelling of 13138781 in words is "thirteen million, one hundred thirty-eight thousand, seven hundred eighty-one".