13538781 has 24 divisors (see below), whose sum is σ = 20323160. Its totient is φ = 8678016.

The previous prime is 13538779. The next prime is 13538813. The reversal of 13538781 is 18783531.

It can be written as a sum of positive squares in 4 ways, for example, as 6200100 + 7338681 = 2490^2 + 2709^2 .

It is not a de Polignac number, because 13538781 - 2¹ = 13538779 is a prime.

It is a super-2 number, since 2×13538781² = 366597181931922, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13538731) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36111 + ... + 36483.

Almost surely, 2^13538781 is an apocalyptic number.

It is an amenable number.

13538781 is a deficient number, since it is larger than the sum of its proper divisors (6784379).

13538781 is a wasteful number, since it uses less digits than its factorization.

13538781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525 (or 522 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 13538781 is about 3679.5082551885. The cubic root of 13538781 is about 238.3379435212.

The spelling of 13538781 in words is "thirteen million, five hundred thirty-eight thousand, seven hundred eighty-one".