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1640 = 23541
BaseRepresentation
bin11001101000
32020202
4121220
523030
611332
74532
oct3150
92222
101640
111261
12b48
13992
14852
15745
hex668

1640 has 16 divisors (see below), whose sum is σ = 3780. Its totient is φ = 640.

The previous prime is 1637. The next prime is 1657. The reversal of 1640 is 461.

1640 is nontrivially palindromic in base 3 and base 9.

It can be written as a sum of positive squares in 2 ways, for example, as 1444 + 196 = 38^2 + 14^2 .

1640 is an undulating number in base 3.

1640 is a nontrivial repdigit in base 9.

It is a plaindrome in base 9 and base 16.

It is a nialpdrome in base 9, base 13 and base 14.

It is a zygodrome in base 9.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 20 + ... + 60.

21640 is an apocalyptic number.

1640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a pronic number, being equal to 40×41.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1890).

1640 is an abundant number, since it is smaller than the sum of its proper divisors (2140).

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

1640 is a wasteful number, since it uses less digits than its factorization.

1640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 1640 is about 40.4969134626. The cubic root of 1640 is about 11.7927370799.

The spelling of 1640 in words is "one thousand, six hundred forty".

Divisors: 1 2 4 5 8 10 20 40 41 82 164 205 328 410 820 1640