1218328813 has 4 divisors (see below), whose sum is σ = 1312046428. Its totient is φ = 1124611200.

The previous prime is 1218328789. The next prime is 1218328841. The reversal of 1218328813 is 3188238121.

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 402483844 + 815844969 = 20062^2 + 28563^2 .

It is a cyclic number.

It is not a de Polignac number, because 1218328813 - 2¹⁷ = 1218197741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1218328843) 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, 46858788 + ... + 46858813.

It is an arithmetic number, because the mean of its divisors is an integer number (328011607).

Almost surely, 2^1218328813 is an apocalyptic number.

1218328813 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

1218328813 is a deficient number, since it is larger than the sum of its proper divisors (93717615).

1218328813 is an equidigital number, since it uses as much as digits as its factorization.

1218328813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93717614.

The product of its digits is 18432, while the sum is 37.

The square root of 1218328813 is about 34904.5672226429. The cubic root of 1218328813 is about 1068.0416074749.

It can be divided in two parts, 1218328 and 813, that added together give a triangular number (1219141 = T₁₅₆₁).

The spelling of 1218328813 in words is "one billion, two hundred eighteen million, three hundred twenty-eight thousand, eight hundred thirteen".