12121616 has 40 divisors (see below), whose sum is σ = 25586904. Its totient is φ = 5529600.

The previous prime is 12121583. The next prime is 12121619. The reversal of 12121616 is 61612121.

It can be written as a sum of positive squares in 4 ways, for example, as 6739216 + 5382400 = 2596^2 + 2320^2 .

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 (12121619) 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 7 ways as a sum of consecutive naturals, for example, 20720 + ... + 21296.

Almost surely, 2^12121616 is an apocalyptic number.

12121616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 12121616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12793452).

12121616 is an abundant number, since it is smaller than the sum of its proper divisors (13465288).

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

12121616 is a wasteful number, since it uses less digits than its factorization.

12121616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699 (or 693 counting only the distinct ones).

The product of its digits is 144, while the sum is 20.

The square root of 12121616 is about 3481.6111213058. The cubic root of 12121616 is about 229.7136701574.

Adding to 12121616 its reverse (61612121), we get a palindrome (73733737).

The spelling of 12121616 in words is "twelve million, one hundred twenty-one thousand, six hundred sixteen".