321907921 has 2 divisors, whose sum is σ = 321907922. Its totient is φ = 321907920.

The previous prime is 321907913. The next prime is 321907939. The reversal of 321907921 is 129709123.

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., 312016896 + 9891025 = 17664^2 + 3145^2 .

It is an emirp because it is prime and its reverse (129709123) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 321907921 - 2³ = 321907913 is a prime.

It is not a weakly prime, because it can be changed into another prime (321907951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160953960 + 160953961.

It is an arithmetic number, because the mean of its divisors is an integer number (160953961).

Almost surely, 2^321907921 is an apocalyptic number.

It is an amenable number.

321907921 is a deficient number, since it is larger than the sum of its proper divisors (1).

321907921 is an equidigital number, since it uses as much as digits as its factorization.

321907921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6804, while the sum is 34.

The square root of 321907921 is about 17941.7925804530. The cubic root of 321907921 is about 685.3470605299.

The spelling of 321907921 in words is "three hundred twenty-one million, nine hundred seven thousand, nine hundred twenty-one".