640464 has 40 divisors (see below), whose sum is σ = 1806432. Its totient is φ = 193920.

The previous prime is 640463. The next prime is 640477. The reversal of 640464 is 464046.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an Ulam number.

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 640464.

It is not an unprimeable number, because it can be changed into a prime (640463) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79 + ... + 1134.

2⁶⁴⁰⁴⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (903216).

640464 is an abundant number, since it is smaller than the sum of its proper divisors (1165968).

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

640464 is a wasteful number, since it uses less digits than its factorization.

640464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1235 (or 1229 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

The square root of 640464 is about 800.2899474565. The cubic root of 640464 is about 86.1982087723.

It can be divided in two parts, 6 and 40464, that added together give a triangular number (40470 = T₂₈₄).

The spelling of 640464 in words is "six hundred forty thousand, four hundred sixty-four".