13721721 has 16 divisors (see below), whose sum is σ = 19815936. Its totient is φ = 8395776.

The previous prime is 13721713. The next prime is 13721723. The reversal of 13721721 is 12712731.

It is not a de Polignac number, because 13721721 - 2³ = 13721713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 13721691 and 13721700.

It is not an unprimeable number, because it can be changed into a prime (13721723) 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 15 ways as a sum of consecutive naturals, for example, 6616 + ... + 8438.

It is an arithmetic number, because the mean of its divisors is an integer number (1238496).

Almost surely, 2^13721721 is an apocalyptic number.

It is an amenable number.

13721721 is a deficient number, since it is larger than the sum of its proper divisors (6094215).

13721721 is a wasteful number, since it uses less digits than its factorization.

13721721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2032.

The product of its digits is 588, while the sum is 24.

The square root of 13721721 is about 3704.2841413693. The cubic root of 13721721 is about 239.4066418734.

The spelling of 13721721 in words is "thirteen million, seven hundred twenty-one thousand, seven hundred twenty-one".