13671781 has 2 divisors, whose sum is σ = 13671782. Its totient is φ = 13671780.

The previous prime is 13671769. The next prime is 13671787. The reversal of 13671781 is 18717631.

13671781 is digitally balanced in base 2, 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., 13322500 + 349281 = 3650^2 + 591^2 .

It is a cyclic number.

It is not a de Polignac number, because 13671781 - 2⁷ = 13671653 is a prime.

It is a super-2 number, since 2×13671781² = 373835191423922, which contains 22 as substring.

It is a zygodrome in base 5.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13671787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6835890 + 6835891.

It is an arithmetic number, because the mean of its divisors is an integer number (6835891).

Almost surely, 2^13671781 is an apocalyptic number.

It is an amenable number.

13671781 is a deficient number, since it is larger than the sum of its proper divisors (1).

13671781 is an equidigital number, since it uses as much as digits as its factorization.

13671781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7056, while the sum is 34.

The square root of 13671781 is about 3697.5371532954. The cubic root of 13671781 is about 239.1158498361.

It can be divided in two parts, 136 and 71781, that added together give a palindrome (71917).

The spelling of 13671781 in words is "thirteen million, six hundred seventy-one thousand, seven hundred eighty-one".