20808218 has 4 divisors (see below), whose sum is σ = 31212330. Its totient is φ = 10404108.

The previous prime is 20808107. The next prime is 20808233. The reversal of 20808218 is 81280802.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 14341369 + 6466849 = 3787^2 + 2543^2 .

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 as a sum of consecutive naturals, namely, 5202053 + ... + 5202056.

Almost surely, 2^20808218 is an apocalyptic number.

20808218 is a deficient number, since it is larger than the sum of its proper divisors (10404112).

20808218 is a wasteful number, since it uses less digits than its factorization.

20808218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10404111.

The product of its (nonzero) digits is 2048, while the sum is 29.

The square root of 20808218 is about 4561.6025692732. The cubic root of 20808218 is about 275.0499876073.

The spelling of 20808218 in words is "twenty million, eight hundred eight thousand, two hundred eighteen".