13681681 has 4 divisors (see below), whose sum is σ = 14734132. Its totient is φ = 12629232.

The previous prime is 13681673. The next prime is 13681693. The reversal of 13681681 is 18618631.

13681681 = 2615² + 2616².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18618631 = 31 ⋅600601.

It can be written as a sum of positive squares in 2 ways, for example, as 6843456 + 6838225 = 2616^2 + 2615^2 .

It is a cyclic number.

It is not a de Polignac number, because 13681681 - 2³ = 13681673 is a prime.

It is a super-2 number, since 2×13681681² = 374376789971522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13681621) 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, 526206 + ... + 526231.

It is an arithmetic number, because the mean of its divisors is an integer number (3683533).

Almost surely, 2^13681681 is an apocalyptic number.

13681681 is the 2616-th centered square number.

It is an amenable number.

13681681 is a deficient number, since it is larger than the sum of its proper divisors (1052451).

13681681 is a wasteful number, since it uses less digits than its factorization.

13681681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1052450.

The product of its digits is 6912, while the sum is 34.

The square root of 13681681 is about 3698.8756399749. The cubic root of 13681681 is about 239.1735520416.

The spelling of 13681681 in words is "thirteen million, six hundred eighty-one thousand, six hundred eighty-one".