640370609 has 2 divisors, whose sum is σ = 640370610. Its totient is φ = 640370608.

The previous prime is 640370587. The next prime is 640370639. The reversal of 640370609 is 906073046.

640370609 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., 508051600 + 132319009 = 22540^2 + 11503^2 .

It is a cyclic number.

It is not a de Polignac number, because 640370609 - 2²⁸ = 371935153 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640370639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320185304 + 320185305.

It is an arithmetic number, because the mean of its divisors is an integer number (320185305).

Almost surely, 2^640370609 is an apocalyptic number.

It is an amenable number.

640370609 is a deficient number, since it is larger than the sum of its proper divisors (1).

640370609 is an equidigital number, since it uses as much as digits as its factorization.

640370609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 35.

The square root of 640370609 is about 25305.5450247569. The cubic root of 640370609 is about 861.9401882656.

The spelling of 640370609 in words is "six hundred forty million, three hundred seventy thousand, six hundred nine".