13121921 has 2 divisors, whose sum is σ = 13121922. Its totient is φ = 13121920.

The previous prime is 13121887. The next prime is 13121971. The reversal of 13121921 is 12912131.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8439025 + 4682896 = 2905^2 + 2164^2 .

It is a cyclic number.

It is not a de Polignac number, because 13121921 - 2¹⁰ = 13120897 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 13121893 and 13121902.

It is not a weakly prime, because it can be changed into another prime (13121971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6560960 + 6560961.

It is an arithmetic number, because the mean of its divisors is an integer number (6560961).

Almost surely, 2^13121921 is an apocalyptic number.

It is an amenable number.

13121921 is a deficient number, since it is larger than the sum of its proper divisors (1).

13121921 is an equidigital number, since it uses as much as digits as its factorization.

13121921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108, while the sum is 20.

The square root of 13121921 is about 3622.4192192511. The cubic root of 13121921 is about 235.8662521386.

The spelling of 13121921 in words is "thirteen million, one hundred twenty-one thousand, nine hundred twenty-one".