13687721 has 2 divisors, whose sum is σ = 13687722. Its totient is φ = 13687720.

The previous prime is 13687699. The next prime is 13687741. The reversal of 13687721 is 12778631.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12390400 + 1297321 = 3520^2 + 1139^2 .

It is a cyclic number.

It is not a de Polignac number, because 13687721 - 2²² = 9493417 is a prime.

It is a super-3 number, since 3×13687721³ (a number of 22 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (13687741) 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, 6843860 + 6843861.

It is an arithmetic number, because the mean of its divisors is an integer number (6843861).

Almost surely, 2^13687721 is an apocalyptic number.

It is an amenable number.

13687721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13687721 is an equidigital number, since it uses as much as digits as its factorization.

13687721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 35.

The square root of 13687721 is about 3699.6920142088. The cubic root of 13687721 is about 239.2087425450.

The spelling of 13687721 in words is "thirteen million, six hundred eighty-seven thousand, seven hundred twenty-one".