19961321 has 2 divisors, whose sum is σ = 19961322. Its totient is φ = 19961320.

The previous prime is 19961317. The next prime is 19961327. The reversal of 19961321 is 12316991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18835600 + 1125721 = 4340^2 + 1061^2 .

It is an emirp because it is prime and its reverse (12316991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19961321 - 2² = 19961317 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19961327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9980660 + 9980661.

It is an arithmetic number, because the mean of its divisors is an integer number (9980661).

Almost surely, 2^19961321 is an apocalyptic number.

It is an amenable number.

19961321 is a deficient number, since it is larger than the sum of its proper divisors (1).

19961321 is an equidigital number, since it uses as much as digits as its factorization.

19961321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2916, while the sum is 32.

The square root of 19961321 is about 4467.8094184958. The cubic root of 19961321 is about 271.2666638024.

The spelling of 19961321 in words is "nineteen million, nine hundred sixty-one thousand, three hundred twenty-one".