1218297861 has 64 divisors (see below), whose sum is σ = 2052218880. Its totient is φ = 707616000.

The previous prime is 1218297851. The next prime is 1218297869. The reversal of 1218297861 is 1687928121.

It is not a de Polignac number, because 1218297861 - 2⁹ = 1218297349 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 (1218297869) 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 63 ways as a sum of consecutive naturals, for example, 1039806 + ... + 1040976.

It is an arithmetic number, because the mean of its divisors is an integer number (32065920).

Almost surely, 2^1218297861 is an apocalyptic number.

1218297861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1218297861 is a deficient number, since it is larger than the sum of its proper divisors (833921019).

1218297861 is a wasteful number, since it uses less digits than its factorization.

1218297861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1335 (or 1329 counting only the distinct ones).

The product of its digits is 96768, while the sum is 45.

The square root of 1218297861 is about 34904.1238394548. The cubic root of 1218297861 is about 1068.0325627617.

The spelling of 1218297861 in words is "one billion, two hundred eighteen million, two hundred ninety-seven thousand, eight hundred sixty-one".