640656067 has 6 divisors (see below), whose sum is σ = 680558828. Its totient is φ = 602970144.

The previous prime is 640656061. The next prime is 640656089. The reversal of 640656067 is 760656046.

640656067 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 640656067 - 2¹¹ = 640654019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640656061) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1108113 + ... + 1108690.

Almost surely, 2^640656067 is an apocalyptic number.

640656067 is a deficient number, since it is larger than the sum of its proper divisors (39902761).

640656067 is a wasteful number, since it uses less digits than its factorization.

640656067 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2216837 (or 2216820 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 40.

The square root of 640656067 is about 25311.1846226130. The cubic root of 640656067 is about 862.0682449293.

The spelling of 640656067 in words is "six hundred forty million, six hundred fifty-six thousand, sixty-seven".