18121718 has 8 divisors (see below), whose sum is σ = 27205848. Its totient is φ = 9053104.

The previous prime is 18121709. The next prime is 18121721. The reversal of 18121718 is 81712181.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-3 number, since 3×18121718³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 296 + ... + 6027.

It is an arithmetic number, because the mean of its divisors is an integer number (3400731).

Almost surely, 2^18121718 is an apocalyptic number.

18121718 is a deficient number, since it is larger than the sum of its proper divisors (9084130).

18121718 is a wasteful number, since it uses less digits than its factorization.

18121718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7758.

The product of its digits is 896, while the sum is 29.

The square root of 18121718 is about 4256.9611226789. The cubic root of 18121718 is about 262.6635377017.

Adding to 18121718 its reverse (81712181), we get a palindrome (99833899).

The spelling of 18121718 in words is "eighteen million, one hundred twenty-one thousand, seven hundred eighteen".