640606 has 4 divisors (see below), whose sum is σ = 960912. Its totient is φ = 320302.

The previous prime is 640589. The next prime is 640613. The reversal of 640606 is 606046.

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

640606 is a modest number, since divided by 606 gives 64 as remainder.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 160150 + ... + 160153.

It is an arithmetic number, because the mean of its divisors is an integer number (240228).

2⁶⁴⁰⁶⁰⁶ is an apocalyptic number.

640606 is a deficient number, since it is larger than the sum of its proper divisors (320306).

640606 is a wasteful number, since it uses less digits than its factorization.

640606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320305.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 640606 is about 800.3786603852. The cubic root of 640606 is about 86.2045787588.

The spelling of 640606 in words is "six hundred forty thousand, six hundred six".