640470 has 32 divisors (see below), whose sum is σ = 1581408. Its totient is φ = 165888.

The previous prime is 640463. The next prime is 640477. The reversal of 640470 is 74046.

It is an interprime number because it is at equal distance from previous prime (640463) and next prime (640477).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640470.

It is not an unprimeable number, because it can be changed into a prime (640477) by changing a digit.

640470 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 15 ways as a sum of consecutive naturals, for example, 822 + ... + 1398.

It is an arithmetic number, because the mean of its divisors is an integer number (49419).

2⁶⁴⁰⁴⁷⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640470, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (790704).

640470 is an abundant number, since it is smaller than the sum of its proper divisors (940938).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640470 is a wasteful number, since it uses less digits than its factorization.

640470 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 640470 is about 800.2936960891. The cubic root of 640470 is about 86.1984779457.

The spelling of 640470 in words is "six hundred forty thousand, four hundred seventy".