663875921 has 2 divisors, whose sum is σ = 663875922. Its totient is φ = 663875920.

The previous prime is 663875911. The next prime is 663875923. The reversal of 663875921 is 129578366.

663875921 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., 357625921 + 306250000 = 18911^2 + 17500^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-663875921 is a prime.

Together with 663875923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (663875923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331937960 + 331937961.

It is an arithmetic number, because the mean of its divisors is an integer number (331937961).

Almost surely, 2^663875921 is an apocalyptic number.

It is an amenable number.

663875921 is a deficient number, since it is larger than the sum of its proper divisors (1).

663875921 is an equidigital number, since it uses as much as digits as its factorization.

663875921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 544320, while the sum is 47.

The square root of 663875921 is about 25765.7897414382. The cubic root of 663875921 is about 872.3597894031.

The spelling of 663875921 in words is "six hundred sixty-three million, eight hundred seventy-five thousand, nine hundred twenty-one".