20985885 has 20 divisors (see below), whose sum is σ = 37619868. Its totient is φ = 11192256.

The previous prime is 20985883. The next prime is 20985889. The reversal of 20985885 is 58858902.

It can be written as a sum of positive squares in 2 ways, for example, as 7634169 + 13351716 = 2763^2 + 3654^2 .

It is not a de Polignac number, because 20985885 - 2¹ = 20985883 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20985885.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20985883) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 25504 + ... + 26313.

Almost surely, 2^20985885 is an apocalyptic number.

It is an amenable number.

20985885 is a deficient number, since it is larger than the sum of its proper divisors (16633983).

20985885 is an equidigital number, since it uses as much as digits as its factorization.

20985885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51834 (or 51825 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 45.

The square root of 20985885 is about 4581.0353633213. The cubic root of 20985885 is about 275.8305907446.

The spelling of 20985885 in words is "twenty million, nine hundred eighty-five thousand, eight hundred eighty-five".