2821

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Summary

Factorization

The number 2821 is a square-free number with prime factors 7, 13, and 31. The prime factorization is as follows:

$\!2821=7\cdot 13\cdot 31$

Properties and families

Property or family	Parameter values	First few members	Proof of membership/containment/satisfaction
Carmichael number	fifth among them	561, 1105, 1729, 2465, 2821, 6601, [SHOW MORE] 8911, 10585, 15841, 29341, 41041, 46657, 52633, 62745, 63973, 75361, 101101, 115921, 126217, 162401, 172081, 188461, 252601, 278545, 294409, 314821, 334153, 340561, 399001, 410041, 449065, 488881, 512461 View list on OEIS	The universal exponent is $\operatorname {lcm} \{6,12,30\}=60$ which divides 2821 - 1 = 2820.
Poulet number (Fermat pseudoprime to base 2)	eleventh among them	341, 561, 645, 1105, 1387, 1729, 1905, 2047, [SHOW MORE] 2465, 2701, 2821, 3277, 4033, 4369, 4371, 4681, 5461, 6601, 7957, 8321, 8481, 8911, 10261, 10585, 11305, 12801, 13741, 13747, 13981, 14491, 15709, 15841, 16705, 18705, 18721, 19951, 23001, 23377, 25761, 29341 View list on OEIS	follows from being a Carmichael number.