13647721 has 2 divisors, whose sum is σ = 13647722. Its totient is φ = 13647720.

The previous prime is 13647701. The next prime is 13647731. The reversal of 13647721 is 12774631.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13039321 + 608400 = 3611^2 + 780^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13647721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (13647701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6823860 + 6823861.

It is an arithmetic number, because the mean of its divisors is an integer number (6823861).

Almost surely, 2^13647721 is an apocalyptic number.

It is an amenable number.

13647721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13647721 is an equidigital number, since it uses as much as digits as its factorization.

13647721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 31.

The square root of 13647721 is about 3694.2822036222. The cubic root of 13647721 is about 238.9754997848.

The spelling of 13647721 in words is "thirteen million, six hundred forty-seven thousand, seven hundred twenty-one".