39
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Number
$39$ (thirty-nine) is:
- $3 \times 13$
- The smallest positive integer having a multiplicative persistence of $3$.
- The $15$th semiprime after $4$, $6$, $9$, $10$, $14$, $15$, $21$, $22$, $25$, $26$, $33$, $34$, $35$, $38$:
- $39 = 3 \times 13$
- The $21$st after $1$, $2$, $4$, $5$, $6$, $8$, $9$, $12$, $13$, $15$, $16$, $17$, $20$, $24$, $25$, $27$, $28$, $32$, $35$, $26$ of the $24$ positive integers which cannot be expressed as the sum of distinct non-pythagorean primes.
- The $28$th integer $n$ such that $2^n$ contains no zero in its decimal representation:
- $2^{39} = 549 \, 755 \, 813 \, 888$
- The number of convex polygons that can be assembled from the complete set of $12$ hexiamonds.
- Suggested by David Wells in his $1986$ book Curious and Interesting Numbers as being the smallest uninteresting number, which fact makes it intrinsically interesting.
Also see
- Previous ... Next: Smallest Arguments for given Multiplicative Persistence
- Previous ... Next: Positive Integers Not Expressible as Sum of Distinct Non-Pythagorean Primes
- Previous ... Next: Powers of 2 with no Zero in Decimal Representation
- Previous ... Next: Semiprime Number
Sources
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $39$