12981618 has 48 divisors (see below), whose sum is σ = 31351320. Its totient is φ = 3854592.

The previous prime is 12981613. The next prime is 12981623. The reversal of 12981618 is 81618921.

It is an interprime number because it is at equal distance from previous prime (12981613) and next prime (12981623).

It can be written as a sum of positive squares in 4 ways, for example, as 11309769 + 1671849 = 3363^2 + 1293^2 .

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

It is not an unprimeable number, because it can be changed into a prime (12981611) 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 23 ways as a sum of consecutive naturals, for example, 5830 + ... + 7742.

Almost surely, 2^12981618 is an apocalyptic number.

12981618 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 12981618, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15675660).

12981618 is an abundant number, since it is smaller than the sum of its proper divisors (18369702).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

12981618 is a wasteful number, since it uses less digits than its factorization.

12981618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1963 (or 1960 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 12981618 is about 3603.0012489590. The cubic root of 12981618 is about 235.0225902533.

It can be divided in two parts, 1298 and 1618, that added together give a square (2916 = 54²).

The spelling of 12981618 in words is "twelve million, nine hundred eighty-one thousand, six hundred eighteen".