1218380851 has 4 divisors (see below), whose sum is σ = 1218786912. Its totient is φ = 1217974792.

The previous prime is 1218380809. The next prime is 1218380873. The reversal of 1218380851 is 1580838121.

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

It is a cyclic number.

It is not a de Polignac number, because 1218380851 - 2²³ = 1209992243 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1218380851.

It is not an unprimeable number, because it can be changed into a prime (1218380651) 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 3 ways as a sum of consecutive naturals, for example, 198496 + ... + 204541.

It is an arithmetic number, because the mean of its divisors is an integer number (304696728).

Almost surely, 2^1218380851 is an apocalyptic number.

1218380851 is a deficient number, since it is larger than the sum of its proper divisors (406061).

1218380851 is an equidigital number, since it uses as much as digits as its factorization.

1218380851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406060.

The product of its (nonzero) digits is 15360, while the sum is 37.

The square root of 1218380851 is about 34905.3126472175. The cubic root of 1218380851 is about 1068.0568135389.

The spelling of 1218380851 in words is "one billion, two hundred eighteen million, three hundred eighty thousand, eight hundred fifty-one".