11 (number) "ùndici" (but in Spanish and Portuguese, 16, and in French, 17 is the first compound number), Chinese 十一 "shí yī", Korean 열한 "yeol han". 11 is a prime number. It is the smallest two-digit prime number in the decimal base. The next prime is 13, with which it comprises a twin prime. If a number is divisible by 11, reversing its digits will result in another multiple of 11. As long as no two adjacent digits of a number added together exceed 9, then multiplying the number by 11, reversing the digits of the product, and dividing that new number
400 (number) consecutive primes (17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53 + 59 + 61) A prime number, Chen prime, sexy prime with 467, Eisenstein prime with no imaginary part 462 = 2 × 3 × 7 × 11, binomial coefficient formula_2, sum of six consecutive primes (67 + 71 + 73 + 79 + 83 + 89), pronic number, sparsely totient number A prime number, sum of seven consecutive primes (53 + 59 + 61 + 67 + 71 + 73 + 79), centered heptagonal number, 464 = 2