640718 has 16 divisors (see below), whose sum is σ = 1090320. Its totient is φ = 279936.

The previous prime is 640691. The next prime is 640727. The reversal of 640718 is 817046.

It is a Harshad number since it is a multiple of its sum of digits (26).

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 in 7 ways as a sum of consecutive naturals, for example, 155 + ... + 1142.

It is an arithmetic number, because the mean of its divisors is an integer number (68145).

2⁶⁴⁰⁷¹⁸ is an apocalyptic number.

640718 is a deficient number, since it is larger than the sum of its proper divisors (449602).

640718 is a wasteful number, since it uses less digits than its factorization.

640718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1331.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 640718 is about 800.4486242102. The cubic root of 640718 is about 86.2096023096.

The spelling of 640718 in words is "six hundred forty thousand, seven hundred eighteen".