1218366641 has 4 divisors (see below), whose sum is σ = 1218904932. Its totient is φ = 1217828352.

The previous prime is 1218366637. The next prime is 1218366671. The reversal of 1218366641 is 1466638121.

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 990990400 + 227376241 = 31480^2 + 15079^2 .

It is a cyclic number.

It is not a de Polignac number, because 1218366641 - 2² = 1218366637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1218366595 and 1218366604.

It is not an unprimeable number, because it can be changed into a prime (1218366631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 265736 + ... + 270281.

It is an arithmetic number, because the mean of its divisors is an integer number (304726233).

Almost surely, 2^1218366641 is an apocalyptic number.

It is an amenable number.

1218366641 is a deficient number, since it is larger than the sum of its proper divisors (538291).

1218366641 is an equidigital number, since it uses as much as digits as its factorization.

1218366641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538290.

The product of its digits is 41472, while the sum is 38.

The square root of 1218366641 is about 34905.1090959475. The cubic root of 1218366641 is about 1068.0526612668.

The spelling of 1218366641 in words is "one billion, two hundred eighteen million, three hundred sixty-six thousand, six hundred forty-one".