4903921

Appears in sequences

• Absolute Euler pseudoprimes: odd composite numbers n such that a^((n-1)/2) == +-1 (mod n) for every a coprime to n.at n=30A033181
• Carmichael numbers C such that C-1 is not a Niven/Harshad number.at n=14A097061
• Carmichael numbers divisible by 11.at n=9A182090
• Carmichael numbers divisible by 31.at n=12A182151
• Numbers n > 2 such that A258409(n)*A002322(n) divides n-1.at n=11A284671
• Carmichael numbers k such that phi(k) divides (k-1)*lambda(k).at n=17A306338
• The lesser of twin Carmichael numbers: a pair of consecutive Carmichael numbers (A002997) without a non-prime-power weak Carmichael number (A087442) between them.at n=8A365022