640768723 has 4 divisors (see below), whose sum is σ = 732307120. Its totient is φ = 549230328.

The previous prime is 640768703. The next prime is 640768741. The reversal of 640768723 is 327867046.

It is a happy number.

640768723 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640768723 - 2⁹ = 640768211 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640768723.

It is not an unprimeable number, because it can be changed into a prime (640768703) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45769188 + ... + 45769201.

It is an arithmetic number, because the mean of its divisors is an integer number (183076780).

Almost surely, 2^640768723 is an apocalyptic number.

640768723 is a deficient number, since it is larger than the sum of its proper divisors (91538397).

640768723 is an equidigital number, since it uses as much as digits as its factorization.

640768723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91538396.

The product of its (nonzero) digits is 338688, while the sum is 43.

The square root of 640768723 is about 25313.4099441383. The cubic root of 640768723 is about 862.1187720234.

The spelling of 640768723 in words is "six hundred forty million, seven hundred sixty-eight thousand, seven hundred twenty-three".