13491721 has 2 divisors, whose sum is σ = 13491722. Its totient is φ = 13491720.

The previous prime is 13491703. The next prime is 13491743. The reversal of 13491721 is 12719431.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10017225 + 3474496 = 3165^2 + 1864^2 .

It is a cyclic number.

It is not a de Polignac number, because 13491721 - 2⁵ = 13491689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 13491721.

It is not a weakly prime, because it can be changed into another prime (13431721) 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, 6745860 + 6745861.

It is an arithmetic number, because the mean of its divisors is an integer number (6745861).

Almost surely, 2^13491721 is an apocalyptic number.

It is an amenable number.

13491721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13491721 is an equidigital number, since it uses as much as digits as its factorization.

13491721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 28.

The square root of 13491721 is about 3673.1078121939. The cubic root of 13491721 is about 238.0614734222.

The spelling of 13491721 in words is "thirteen million, four hundred ninety-one thousand, seven hundred twenty-one".