664043641 has 2 divisors, whose sum is σ = 664043642. Its totient is φ = 664043640.

The previous prime is 664043629. The next prime is 664043651. The reversal of 664043641 is 146340466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 590684416 + 73359225 = 24304^2 + 8565^2 .

It is a cyclic number.

It is not a de Polignac number, because 664043641 - 2⁵ = 664043609 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 664043597 and 664043606.

It is not a weakly prime, because it can be changed into another prime (664043651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332021820 + 332021821.

It is an arithmetic number, because the mean of its divisors is an integer number (332021821).

Almost surely, 2^664043641 is an apocalyptic number.

It is an amenable number.

664043641 is a deficient number, since it is larger than the sum of its proper divisors (1).

664043641 is an equidigital number, since it uses as much as digits as its factorization.

664043641 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 664043641 is about 25769.0442391642. The cubic root of 664043641 is about 872.4332468367.

The spelling of 664043641 in words is "six hundred sixty-four million, forty-three thousand, six hundred forty-one".