18121616 has 10 divisors (see below), whose sum is σ = 35110662. Its totient is φ = 9060800.

The previous prime is 18121613. The next prime is 18121633. The reversal of 18121616 is 61612181.

It can be written as a sum of positive squares in only one way, i.e., 14137600 + 3984016 = 3760^2 + 1996^2 .

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 (18121613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 566285 + ... + 566316.

Almost surely, 2^18121616 is an apocalyptic number.

18121616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

18121616 is a deficient number, since it is larger than the sum of its proper divisors (16989046).

18121616 is a wasteful number, since it uses less digits than its factorization.

18121616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1132609 (or 1132603 counting only the distinct ones).

The product of its digits is 576, while the sum is 26.

The square root of 18121616 is about 4256.9491422849. The cubic root of 18121616 is about 262.6630448910.

Adding to 18121616 its reverse (61612181), we get a palindrome (79733797).

The spelling of 18121616 in words is "eighteen million, one hundred twenty-one thousand, six hundred sixteen".