13706721 has 18 divisors (see below), whose sum is σ = 23031762. Its totient is φ = 7832160.

The previous prime is 13706717. The next prime is 13706731. The reversal of 13706721 is 12760731.

It can be written as a sum of positive squares in only one way, i.e., 10595025 + 3111696 = 3255^2 + 1764^2 .

It is not a de Polignac number, because 13706721 - 2² = 13706717 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13706731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 15100 + ... + 15981.

Almost surely, 2^13706721 is an apocalyptic number.

It is an amenable number.

13706721 is a deficient number, since it is larger than the sum of its proper divisors (9325041).

13706721 is a wasteful number, since it uses less digits than its factorization.

13706721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31101 (or 31091 counting only the distinct ones).

The product of its (nonzero) digits is 1764, while the sum is 27.

The square root of 13706721 is about 3702.2589050470. The cubic root of 13706721 is about 239.3193736906.

The spelling of 13706721 in words is "thirteen million, seven hundred six thousand, seven hundred twenty-one".