212320721 has 2 divisors, whose sum is σ = 212320722. Its totient is φ = 212320720.

The previous prime is 212320711. The next prime is 212320729. The reversal of 212320721 is 127023212.

212320721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 210250000 + 2070721 = 14500^2 + 1439^2 .

It is a cyclic number.

It is not a de Polignac number, because 212320721 - 2⁶ = 212320657 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 212320693 and 212320702.

It is not a weakly prime, because it can be changed into another prime (212320729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106160360 + 106160361.

It is an arithmetic number, because the mean of its divisors is an integer number (106160361).

Almost surely, 2^212320721 is an apocalyptic number.

It is an amenable number.

212320721 is a deficient number, since it is larger than the sum of its proper divisors (1).

212320721 is an equidigital number, since it uses as much as digits as its factorization.

212320721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 212320721 is about 14571.2292206251. The cubic root of 212320721 is about 596.5737319061.

Adding to 212320721 its reverse (127023212), we get a palindrome (339343933).

The spelling of 212320721 in words is "two hundred twelve million, three hundred twenty thousand, seven hundred twenty-one".