20865040 has 160 divisors (see below), whose sum is σ = 61067520. Its totient is φ = 6469632.

The previous prime is 20865017. The next prime is 20865041. The reversal of 20865040 is 4056802.

It is a junction number, because it is equal to n+sod(n) for n = 20864996 and 20865014.

It is not an unprimeable number, because it can be changed into a prime (20865041) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 393654 + ... + 393706.

It is an arithmetic number, because the mean of its divisors is an integer number (381672).

Almost surely, 2^20865040 is an apocalyptic number.

20865040 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 20865040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30533760).

20865040 is an abundant number, since it is smaller than the sum of its proper divisors (40202480).

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

20865040 is a wasteful number, since it uses less digits than its factorization.

20865040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 20865040 is about 4567.8266166745. The cubic root of 20865040 is about 275.3001241279.

The spelling of 20865040 in words is "twenty million, eight hundred sixty-five thousand, forty".