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640000 = 21054
BaseRepresentation
bin10011100010000000000
31012111220201
42130100000
5130440000
621414544
75303614
oct2342000
91174821
10640000
113a7929
1226a454
131953ca
14129344
15c996a
hex9c400

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".

Divisors: 1 2 4 5 8 10 16 20 25 32 40 50 64 80 100 125 128 160 200 250 256 320 400 500 512 625 640 800 1000 1024 1250 1280 1600 2000 2500 2560 3200 4000 5000 5120 6400 8000 10000 12800 16000 20000 25600 32000 40000 64000 80000 128000 160000 320000 640000