20818985 has 16 divisors (see below), whose sum is σ = 27438912. Its totient is φ = 15038400.

The previous prime is 20818981. The next prime is 20818997. The reversal of 20818985 is 58981802.

It is not a de Polignac number, because 20818985 - 2² = 20818981 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20818981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7430 + ... + 9840.

It is an arithmetic number, because the mean of its divisors is an integer number (1714932).

Almost surely, 2^20818985 is an apocalyptic number.

It is an amenable number.

20818985 is a deficient number, since it is larger than the sum of its proper divisors (6619927).

20818985 is a wasteful number, since it uses less digits than its factorization.

20818985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2584.

The product of its (nonzero) digits is 46080, while the sum is 41.

The square root of 20818985 is about 4562.7825939880. The cubic root of 20818985 is about 275.0974200299.

The spelling of 20818985 in words is "twenty million, eight hundred eighteen thousand, nine hundred eighty-five".