13661321 has 2 divisors, whose sum is σ = 13661322. Its totient is φ = 13661320.

The previous prime is 13661317. The next prime is 13661327. The reversal of 13661321 is 12316631.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7590025 + 6071296 = 2755^2 + 2464^2 .

It is an emirp because it is prime and its reverse (12316631) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13661321 - 2² = 13661317 is a prime.

It is not a weakly prime, because it can be changed into another prime (13661327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6830660 + 6830661.

It is an arithmetic number, because the mean of its divisors is an integer number (6830661).

Almost surely, 2^13661321 is an apocalyptic number.

It is an amenable number.

13661321 is a deficient number, since it is larger than the sum of its proper divisors (1).

13661321 is an equidigital number, since it uses as much as digits as its factorization.

13661321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 23.

The square root of 13661321 is about 3696.1224276260. The cubic root of 13661321 is about 239.0548533958.

Adding to 13661321 its reverse (12316631), we get a palindrome (25977952).

The spelling of 13661321 in words is "thirteen million, six hundred sixty-one thousand, three hundred twenty-one".