20581218 has 48 divisors (see below), whose sum is σ = 53651520. Its totient is φ = 5570208.

The previous prime is 20581207. The next prime is 20581243. The reversal of 20581218 is 81218502.

It is a junction number, because it is equal to n+sod(n) for n = 20581191 and 20581200.

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 23 ways as a sum of consecutive naturals, for example, 1905 + ... + 6692.

It is an arithmetic number, because the mean of its divisors is an integer number (1117740).

Almost surely, 2^20581218 is an apocalyptic number.

20581218 is an abundant number, since it is smaller than the sum of its proper divisors (33070302).

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

20581218 is a wasteful number, since it uses less digits than its factorization.

20581218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8631 (or 8628 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 20581218 is about 4536.6527308138. The cubic root of 20581218 is about 274.0461410210.

The spelling of 20581218 in words is "twenty million, five hundred eighty-one thousand, two hundred eighteen".