20859840 has 84 divisors (see below), whose sum is σ = 71759064. Its totient is φ = 5561856.

The previous prime is 20859737. The next prime is 20859841. The reversal of 20859840 is 4895802.

20859840 is a `hidden beast` number, since 20 + 8 + 598 + 40 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 20859795 and 20859804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20859841) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 742 + ... + 6501.

Almost surely, 2^20859840 is an apocalyptic number.

20859840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20859840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35879532).

20859840 is an abundant number, since it is smaller than the sum of its proper divisors (50899224).

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

20859840 is a wasteful number, since it uses less digits than its factorization.

20859840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7266 (or 7253 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 20859840 is about 4567.2573827189. The cubic root of 20859840 is about 275.2772520639.

The spelling of 20859840 in words is "twenty million, eight hundred fifty-nine thousand, eight hundred forty".