640618 has 16 divisors (see below), whose sum is σ = 1077984. Its totient is φ = 282960.

The previous prime is 640613. The next prime is 640621. The reversal of 640618 is 816046.

640618 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 640592 and 640601.

It is not an unprimeable number, because it can be changed into a prime (640613) by changing a digit.

640618 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 421 + ... + 1207.

It is an arithmetic number, because the mean of its divisors is an integer number (67374).

2⁶⁴⁰⁶¹⁸ is an apocalyptic number.

640618 is a deficient number, since it is larger than the sum of its proper divisors (437366).

640618 is a wasteful number, since it uses less digits than its factorization.

640618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 837.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 640618 is about 800.3861568018. The cubic root of 640618 is about 86.2051170244.

The spelling of 640618 in words is "six hundred forty thousand, six hundred eighteen".