661,644

2² × 3² × 18379

Starting at 661,644, the Collatz iteration reaches 1 after 154 steps. The first transition is 330822; the starting value is even with 18 positive divisors.

Prime Factor Structure

Factorization String 2^2 × 3^2 × 18379

Distinct Prime Factors 3

Square Status No

Abundance Measure Abundant

Analytical Properties

Total Divisors 18

Divisor Sum (σ) 1,672,580

Proper Divisor Sum 1,010,936

Digit Sum / Digital Root 27 (Root: 9)

Adjacent Primes #661621 ← → #661663

Radix Representation

Decimal	661644
Binary	10100001100010001100 (20 bits)
Octal	0o2414214
Hexadecimal	0xA188C

Divisor Catalog (18)

1 2 3 4 6 9 12 18 36 18,379 36,758 55,137 73,516 110,274 165,411 220,548 330,822 661,644

Collatz Trajectory (154 steps to reach 1)

Iterative sequence n → n/2 (if even) or 3n+1 (if odd):

661,644 330,822 165,411 496,234 248,117 744,352 372,176 186,088 93,044 46,522 23,261 69,784 34,892 17,446 8,723 26,170 13,085 39,256 19,628 9,814 4,907 14,722 7,361 22,084 11,042 5,521 16,564 8,282 4,141 12,424 6,212 3,106 1,553 4,660 2,330 1,165 3,496 1,748 874 437 1,312 656 328 164 82 41 124 62 31 94 47 142 71 214 107 322 161 484 242 121

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