640378169 has 2 divisors, whose sum is σ = 640378170. Its totient is φ = 640378168.

The previous prime is 640378133. The next prime is 640378217. The reversal of 640378169 is 961873046.

640378169 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 630612544 + 9765625 = 25112^2 + 3125^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640378169 is a prime.

It is a super-2 number, since 2×640378169² = 820168398663585122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (640378969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320189084 + 320189085.

It is an arithmetic number, because the mean of its divisors is an integer number (320189085).

Almost surely, 2^640378169 is an apocalyptic number.

It is an amenable number.

640378169 is a deficient number, since it is larger than the sum of its proper divisors (1).

640378169 is an equidigital number, since it uses as much as digits as its factorization.

640378169 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 217728, while the sum is 44.

The square root of 640378169 is about 25305.6943986922. The cubic root of 640378169 is about 861.9435801776.

The spelling of 640378169 in words is "six hundred forty million, three hundred seventy-eight thousand, one hundred sixty-nine".