20857984 has 32 divisors (see below), whose sum is σ = 47491200. Its totient is φ = 8938752.

The previous prime is 20857981. The next prime is 20857999. The reversal of 20857984 is 48975802.

It is a tau number, because it is divible by the number of its divisors (32).

It is a self number, because there is not a number n which added to its sum of digits gives 20857984.

It is not an unprimeable number, because it can be changed into a prime (20857981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10744 + ... + 12535.

It is an arithmetic number, because the mean of its divisors is an integer number (1484100).

Almost surely, 2^20857984 is an apocalyptic number.

It is an amenable number.

20857984 is an abundant number, since it is smaller than the sum of its proper divisors (26633216).

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

20857984 is an equidigital number, since it uses as much as digits as its factorization.

20857984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23300 (or 23288 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 43.

The square root of 20857984 is about 4567.0541928031. The cubic root of 20857984 is about 275.2690875760.

It can be divided in two parts, 2085798 and 4, that added together give a palindrome (2085802).

The spelling of 20857984 in words is "twenty million, eight hundred fifty-seven thousand, nine hundred eighty-four".