20857284 has 96 divisors (see below), whose sum is σ = 63221760. Its totient is φ = 5822496.

The previous prime is 20857247. The next prime is 20857313. The reversal of 20857284 is 48275802.

It is a happy number.

20857284 is a `hidden beast` number, since 2 + 0 + 8 + 572 + 84 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

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 31 ways as a sum of consecutive naturals, for example, 35239 + ... + 35825.

It is an arithmetic number, because the mean of its divisors is an integer number (658560).

Almost surely, 2^20857284 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20857284, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31610880).

20857284 is an abundant number, since it is smaller than the sum of its proper divisors (42364476).

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

20857284 is a wasteful number, since it uses less digits than its factorization.

20857284 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 654 (or 646 counting only the distinct ones).

The product of its (nonzero) digits is 35840, while the sum is 36.

The square root of 20857284 is about 4566.9775563276. The cubic root of 20857284 is about 275.2660081714.

The spelling of 20857284 in words is "twenty million, eight hundred fifty-seven thousand, two hundred eighty-four".