13986781 has 4 divisors (see below), whose sum is σ = 14327964. Its totient is φ = 13645600.

The previous prime is 13986769. The next prime is 13986809. The reversal of 13986781 is 18768931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18768931 = 101 ⋅185831.

It can be written as a sum of positive squares in 2 ways, for example, as 4120900 + 9865881 = 2030^2 + 3141^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13986781 is a prime.

It is a super-2 number, since 2×13986781² = 391260085483922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13986761) 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, 170530 + ... + 170611.

It is an arithmetic number, because the mean of its divisors is an integer number (3581991).

Almost surely, 2^13986781 is an apocalyptic number.

It is an amenable number.

13986781 is a deficient number, since it is larger than the sum of its proper divisors (341183).

13986781 is an equidigital number, since it uses as much as digits as its factorization.

13986781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341182.

The product of its digits is 72576, while the sum is 43.

The square root of 13986781 is about 3739.8905064186. The cubic root of 13986781 is about 240.9383461716.

The spelling of 13986781 in words is "thirteen million, nine hundred eighty-six thousand, seven hundred eighty-one".