1551

1551 = 3 x 11 x 47 (A046329). 1551 is the product of three distinct prime numbers, and the sum of its factors is itself a prime (A176877): 3 + 11 + 47 = 61.

1551 is the number of trees on 25 vertices with diameter 4 (A000094).

1551 is the sum of the first 20 perfect powers (A076408).

1551 is the number of sums payable using exactly 19 banknotes of denominations 1, 5, 10, 20, 50, 100 (A135454).

1551 is a number n such that n² + n - 1 is a prime (A058912).

1551 divides 46¹⁰ - 1.

Source: What's Special About This Number?