643

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643 < 642 | 644 >
All Numbers
600	601	602	603	604	605	606	607	608	609
610	611	612	613	614	615	616	617	618	619
620	621	622	623	624	625	626	627	628	629
630	631	632	633	634	635	636	637	638	639
640	641	642	643	644	645	646	647	648	649
650	651	652	653	654	655	656	657	658	659
660	661	662	663	664	665	666	667	668	669
670	671	672	673	674	675	676	677	678	679
680	681	682	683	684	685	686	687	688	689
690	691	692	693	694	695	696	697	698	699

643 is the number following 642 and preceding 644.

Properties

• It is the 117th prime number.
• 643 is an odd number .
• 643 is an unhappy number.
  

• 643 is deficient.

Approximations

Notation	Lower bound	Upper bound
Up-arrow notation	25 ↑ 2
Scientific notation	6.43 x 102	6.431 x 102
Slow-growing hierarchy	\(g_{\omega^{\omega}}(4)\)	\(g_{\omega^{\omega}}(5)\)
Copy notation	5[3]	6[3]
Chained arrow notation	25 → 2
Bowers' Exploding Array Function/Bird's array notation	{25,2}
Fast-growing hierarchy	f2(6)	f2(7)
Hardy hierarchy	Hω(321)	Hω(322)
Middle-growing hierarchy	m(ω,9)	m(ω,10)
Hyper-E notation	E2.8082
Hyper-E notation (non-10 base)	\(E[25]2\)
Hyperfactorial array notation	5!	6!
X-Sequence Hyper-Exponential Notation	25{1}2
Steinhaus-Moser Notation	4[3]	5[3]
PlantStar's Debut Notation	[1]	[2]
H* function	H(-0.1)	H(-0)
Bashicu matrix system with respect to version 4	(0)[25]	(0)[26]
m(n) map	m(1)(4)	m(1)(5)
s(n) map	\(s(1)(\lambda x . x+1)(320)\)	\(s(1)(\lambda x . x+1)(321)\)