665003921 has 2 divisors, whose sum is σ = 665003922. Its totient is φ = 665003920.

The previous prime is 665003851. The next prime is 665003929. The reversal of 665003921 is 129300566.

It is a happy number.

665003921 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., 335073025 + 329930896 = 18305^2 + 18164^2 .

It is a cyclic number.

It is not a de Polignac number, because 665003921 - 2²⁶ = 597895057 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (665003929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332501960 + 332501961.

It is an arithmetic number, because the mean of its divisors is an integer number (332501961).

Almost surely, 2^665003921 is an apocalyptic number.

It is an amenable number.

665003921 is a deficient number, since it is larger than the sum of its proper divisors (1).

665003921 is an equidigital number, since it uses as much as digits as its factorization.

665003921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 665003921 is about 25787.6699412723. The cubic root of 665003921 is about 872.8535890301.

The spelling of 665003921 in words is "six hundred sixty-five million, three thousand, nine hundred twenty-one".