13401721661 has 2 divisors, whose sum is σ = 13401721662. Its totient is φ = 13401721660.

The previous prime is 13401721643. The next prime is 13401721667. The reversal of 13401721661 is 16612710431.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12542880025 + 858841636 = 111995^2 + 29306^2 .

It is a cyclic number.

It is not a de Polignac number, because 13401721661 - 2¹⁰ = 13401720637 is a prime.

It is a super-2 number, since 2×13401721661² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13401721667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6700860830 + 6700860831.

It is an arithmetic number, because the mean of its divisors is an integer number (6700860831).

Almost surely, 2^13401721661 is an apocalyptic number.

It is an amenable number.

13401721661 is a deficient number, since it is larger than the sum of its proper divisors (1).

13401721661 is an equidigital number, since it uses as much as digits as its factorization.

13401721661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 32.

The spelling of 13401721661 in words is "thirteen billion, four hundred one million, seven hundred twenty-one thousand, six hundred sixty-one".