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Harshad number
A number that is divisible by the sum of its own digits. For example, 1729 is a Harshad number because 1 + 7 + 2 + 9 = 19 and 1729 = 19 × 91. Harshad numbers are also known as Niven numbers.
A Harshad amicable pair is an amicable pair (m, n) such that both m and n are Harshad numbers. For example, 2620 and 2924 are a Harshad amicable pair because 2620 is divisible by 2 + 6 + 2 + 0 = 10 and 2924 is divisible by 2 + 9 + 2 + 4 = 17 (2924/17 = 172). There are 192 Harshad amicable pairs in first 5,000 amicable pairs.
Related category
• TYPES OF NUMBERS
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