1218781 has 4 divisors (see below), whose sum is σ = 1290492. Its totient is φ = 1147072.

The previous prime is 1218779. The next prime is 1218787. The reversal of 1218781 is 1878121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 586756 + 632025 = 766^2 + 795^2 .

It is a cyclic number.

It is not a de Polignac number, because 1218781 - 2¹ = 1218779 is a prime.

It is a super-2 number, since 2×1218781² = 2970854251922, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1218787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35830 + ... + 35863.

It is an arithmetic number, because the mean of its divisors is an integer number (322623).

2^1218781 is an apocalyptic number.

It is an amenable number.

1218781 is a deficient number, since it is larger than the sum of its proper divisors (71711).

1218781 is an equidigital number, since it uses as much as digits as its factorization.

1218781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71710.

The product of its digits is 896, while the sum is 28.

The square root of 1218781 is about 1103.9841484369. The cubic root of 1218781 is about 106.8173726923.

The spelling of 1218781 in words is "one million, two hundred eighteen thousand, seven hundred eighty-one".