640000 has 55 divisors (see below), whose sum is σ = 1598707.
Its totient is φ = 256000.
The previous prime is 639997. The next prime is 640007. The reversal of 640000 is 46.
640000 divided by its sum of digits (10) gives a cube (64000 = 403).
Adding to 640000 its reverse (46), we get a palindrome (640046).
The square root of 640000 is 800.
It is a perfect power (a square), and thus also a powerful number.
It can be written as a sum of positive squares in 2 ways, for example, as 50176 + 589824 = 224^2 + 768^2
It is an ABA number since it can be written as A⋅BA, here for A=4, B=20.
It is a Harshad number since it is a multiple of its sum of digits (10).
It is a Duffinian number.
It is a nialpdrome in base 10.
It is not an unprimeable number, because it can be changed into a prime (640007) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written in 4 ways as a sum of consecutive naturals, for example, 127998 + ... + 128002.
2640000 is an apocalyptic number.
640000 is a droll number since its even prime factors and its odd prime factors have the same sum.
640000 is the 800-th square number.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 640000
640000 is an abundant number, since it is smaller than the sum of its proper divisors (958707).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
640000 is an frugal number, since it uses more digits than its factorization.
640000 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 40 (or 7 counting only the distinct ones).
The product of its (nonzero) digits is 24, while the sum is 10.
The cubic root of 640000 is about 86.1773876013.
The spelling of 640000 in words is "six hundred forty thousand".