1211865 has 16 divisors (see below), whose sum is σ = 1954368. Its totient is φ = 641216.

The previous prime is 1211863. The next prime is 1211897. The reversal of 1211865 is 5681121.

It is a cyclic number.

It is not a de Polignac number, because 1211865 - 2¹ = 1211863 is a prime.

It is a Curzon number.

It is a congruent number.

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 in 15 ways as a sum of consecutive naturals, for example, 2362 + ... + 2828.

It is an arithmetic number, because the mean of its divisors is an integer number (122148).

2^1211865 is an apocalyptic number.

1211865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1211865 is a deficient number, since it is larger than the sum of its proper divisors (742503).

1211865 is a wasteful number, since it uses less digits than its factorization.

1211865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 648.

The product of its digits is 480, while the sum is 24.

The square root of 1211865 is about 1100.8474008690. The cubic root of 1211865 is about 106.6149434562.

Adding to 1211865 its reverse (5681121), we get a palindrome (6892986).

The spelling of 1211865 in words is "one million, two hundred eleven thousand, eight hundred sixty-five".