20806518 has 16 divisors (see below), whose sum is σ = 42955776. Its totient is φ = 6711720.

The previous prime is 20806517. The next prime is 20806519. The reversal of 20806518 is 81560802.

It is an interprime number because it is at equal distance from previous prime (20806517) and next prime (20806519).

It is a super-2 number, since 2×20806518² = 865822382568648, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20806517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55746 + ... + 56117.

It is an arithmetic number, because the mean of its divisors is an integer number (2684736).

Almost surely, 2^20806518 is an apocalyptic number.

20806518 is an abundant number, since it is smaller than the sum of its proper divisors (22149258).

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

20806518 is a wasteful number, since it uses less digits than its factorization.

20806518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111899.

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 20806518 is about 4561.4162274452. The cubic root of 20806518 is about 275.0424970137.

The spelling of 20806518 in words is "twenty million, eight hundred six thousand, five hundred eighteen".