13543721 has 2 divisors, whose sum is σ = 13543722. Its totient is φ = 13543720.

The previous prime is 13543703. The next prime is 13543723. The reversal of 13543721 is 12734531.

13543721 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., 10530025 + 3013696 = 3245^2 + 1736^2 .

It is a cyclic number.

It is not a de Polignac number, because 13543721 - 2¹⁴ = 13527337 is a prime.

Together with 13543723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (13543723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6771860 + 6771861.

It is an arithmetic number, because the mean of its divisors is an integer number (6771861).

Almost surely, 2^13543721 is an apocalyptic number.

It is an amenable number.

13543721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13543721 is an equidigital number, since it uses as much as digits as its factorization.

13543721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 26.

The square root of 13543721 is about 3680.1794793189. The cubic root of 13543721 is about 238.3669280674.

The spelling of 13543721 in words is "thirteen million, five hundred forty-three thousand, seven hundred twenty-one".