399,877,410,625

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Number

$399 \, 877 \, 410 \, 625$ is:

$5^4 \times 7 \times 11 \times 17 \times 23 \times 79 \times 269$

The $26$th square pyramorphic number after $1$, $55$, $5525$, $\ldots$:

$399 \, 877 \, 410 \, 625 = \ds \sum_{k \mathop = 1}^{10 \, 625} k^2 = \dfrac {10 \, 625 \paren {10 \, 625 + 1} \paren {2 \times 10 \, 625 + 1} } 6$

The $10 \, 625$th square pyramidal number:

$399 \, 877 \, 410 \, 625 = \ds \sum_{k \mathop = 1}^{10 \, 625} k^2 = \dfrac {10 \, 625 \paren {10 \, 625 + 1} \paren {2 \times 10 \, 625 + 1} } 6$

Also see

• Previous  ... Next: Square Pyramorphic Number
• Previous  ... Next: Square Pyramidal Number

Sources

• 1991: Clifford A. Pickover: Computers and the Imagination: Chapter $37$: On the Existence of Cakemorphic Integers: Figure $37.4$: Square pyramorphic numbers

• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $399,877,410,625$