# 74

This number is a composite.

The first occurrence of a difference between successive primes of 74 follows 404597. [Lehmer]

22796996699 is the 999799787th prime. Note that the sum of digits of the *n*th prime equals the sum of digits of *n*. The number 74 is the largest known digit sum with this property (as of August 2004). [Firoozbakht]

The only double-digit number ab such that (ab)^a-(ba)^b is prime, i.e., 74^7-47^4 = 12151275393343 that is a prime. [Loungrides]

(There are 3 curios for this number that have not yet been approved by an editor.)

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