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90

90 is the number that succeeds 89 and precedes 91. It is not prime, as 9×10=90. 90 is also the 3rd unitary perfect numbers, as it's divisors (excluding 90) add up to 90[a].


Qualities of 90

  • Is even.
  • Is a sum of two squares, 32 and 92.
  • Is composite.
  • Succeeds a prime number.
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