1211866 has 4 divisors (see below), whose sum is σ = 1817802. Its totient is φ = 605932.

The previous prime is 1211863. The next prime is 1211897. The reversal of 1211866 is 6681121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6681121 = 563 ⋅11867.

It can be written as a sum of positive squares in only one way, i.e., 990025 + 221841 = 995^2 + 471^2 .

It is a super-3 number, since 3×1211866³ = 5339309033392829688, which contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1211866.

It is not an unprimeable number, because it can be changed into a prime (1211863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 302965 + ... + 302968.

2^1211866 is an apocalyptic number.

1211866 is a deficient number, since it is larger than the sum of its proper divisors (605936).

1211866 is an equidigital number, since it uses as much as digits as its factorization.

1211866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 605935.

The product of its digits is 576, while the sum is 25.

The square root of 1211866 is about 1100.8478550644. The cubic root of 1211866 is about 106.6149727815.

Adding to 1211866 its reverse (6681121), we get a palindrome (7892987).

The spelling of 1211866 in words is "one million, two hundred eleven thousand, eight hundred sixty-six".