20985845 has 8 divisors (see below), whose sum is σ = 25863864. Its totient is φ = 16334784.

The previous prime is 20985799. The next prime is 20985847. The reversal of 20985845 is 54858902.

It can be written as a sum of positive squares in 4 ways, for example, as 5414929 + 15570916 = 2327^2 + 3946^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20985845 - 2¹² = 20981749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20985847) 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 7 ways as a sum of consecutive naturals, for example, 56534 + ... + 56903.

It is an arithmetic number, because the mean of its divisors is an integer number (3232983).

Almost surely, 2^20985845 is an apocalyptic number.

It is an amenable number.

20985845 is a deficient number, since it is larger than the sum of its proper divisors (4878019).

20985845 is a wasteful number, since it uses less digits than its factorization.

20985845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113479.

The product of its (nonzero) digits is 115200, while the sum is 41.

The square root of 20985845 is about 4581.0309974939. The cubic root of 20985845 is about 275.8304154962.

The spelling of 20985845 in words is "twenty million, nine hundred eighty-five thousand, eight hundred forty-five".