640567 has 4 divisors (see below), whose sum is σ = 644080. Its totient is φ = 637056.

The previous prime is 640531. The next prime is 640579. The reversal of 640567 is 765046.

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 640567 - 2¹⁹ = 116279 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1467 + ... + 1852.

It is an arithmetic number, because the mean of its divisors is an integer number (161020).

2⁶⁴⁰⁵⁶⁷ is an apocalyptic number.

640567 is a deficient number, since it is larger than the sum of its proper divisors (3513).

640567 is a wasteful number, since it uses less digits than its factorization.

640567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3512.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 640567 is about 800.3542965462. The cubic root of 640567 is about 86.2028293493.

The spelling of 640567 in words is "six hundred forty thousand, five hundred sixty-seven".