13765721 has 2 divisors, whose sum is σ = 13765722. Its totient is φ = 13765720.

The previous prime is 13765673. The next prime is 13765727. The reversal of 13765721 is 12756731.

13765721 is digitally balanced in base 3, 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., 11316496 + 2449225 = 3364^2 + 1565^2 .

It is a cyclic number.

It is not a de Polignac number, because 13765721 - 2¹⁰ = 13764697 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (13765727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6882860 + 6882861.

It is an arithmetic number, because the mean of its divisors is an integer number (6882861).

Almost surely, 2^13765721 is an apocalyptic number.

It is an amenable number.

13765721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13765721 is an equidigital number, since it uses as much as digits as its factorization.

13765721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8820, while the sum is 32.

The square root of 13765721 is about 3710.2184571801. The cubic root of 13765721 is about 239.6622622131.

The spelling of 13765721 in words is "thirteen million, seven hundred sixty-five thousand, seven hundred twenty-one".