972 is the largest number for which the absolute difference between any two digits of the number is always prime.
972 is an Achilles number, which is powerful in the sense that each prime factor occurs with exponent greater than one but imperfect in the sense that the number is not a perfect power.
972 is the sum of four positive fifth powers (A003349): 972 = 35 + 35 + 35 + 35.
Source: Number Gossip
1 comment:
I might be being really dim, but isn't the largest number for which the absolute difference between any two digits is prime, 9742?
(9-7=2; 9-4=5; 9-7=2; 7-4=3; 7-2=5; 4-2=2)
Post a Comment