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666640 = 24513641
BaseRepresentation
bin10100010110000010000
31020212110101
42202300100
5132313030
622142144
75444362
oct2426020
91225411
10666640
11415947
12281954
131a4580
14134d32
15d27ca
hexa2c10

666640 has 40 divisors (see below), whose sum is σ = 1671768. Its totient is φ = 245760.

The previous prime is 666637. The next prime is 666643. The reversal of 666640 is 46666.

It is an interprime number because it is at equal distance from previous prime (666637) and next prime (666643).

It can be written as a sum of positive squares in 4 ways, for example, as 82944 + 583696 = 288^2 + 764^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 666599 and 666608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666643) 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, 720 + ... + 1360.

2666640 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 666640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (835884).

666640 is an abundant number, since it is smaller than the sum of its proper divisors (1005128).

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

666640 is a wasteful number, since it uses less digits than its factorization.

666640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 667 (or 661 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 666640 is about 816.4802508328. The cubic root of 666640 is about 87.3568816841.

The spelling of 666640 in words is "six hundred sixty-six thousand, six hundred forty".

Divisors: 1 2 4 5 8 10 13 16 20 26 40 52 65 80 104 130 208 260 520 641 1040 1282 2564 3205 5128 6410 8333 10256 12820 16666 25640 33332 41665 51280 66664 83330 133328 166660 333320 666640