20718818 has 16 divisors (see below), whose sum is σ = 34042680. Its totient is φ = 9413376.

The previous prime is 20718809. The next prime is 20718823. The reversal of 20718818 is 81881702.

It can be written as a sum of positive squares in 4 ways, for example, as 13712209 + 7006609 = 3703^2 + 2647^2 .

It is a super-5 number, since 5×20718818⁵ (a number of 38 digits) contains 55555 as substring.

It is an unprimeable number.

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, 9521 + ... + 11492.

Almost surely, 2^20718818 is an apocalyptic number.

20718818 is a deficient number, since it is larger than the sum of its proper divisors (13323862).

20718818 is a wasteful number, since it uses less digits than its factorization.

20718818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21061.

The product of its (nonzero) digits is 7168, while the sum is 35.

The square root of 20718818 is about 4551.7928335986. The cubic root of 20718818 is about 274.6555157626.

The spelling of 20718818 in words is "twenty million, seven hundred eighteen thousand, eight hundred eighteen".