20866560 has 320 divisors, whose sum is σ = 82494720. Its totient is φ = 4423680.

The previous prime is 20866529. The next prime is 20866561. The reversal of 20866560 is 6566802.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20866561) 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, 1098231 + ... + 1098249.

It is an arithmetic number, because the mean of its divisors is an integer number (257796).

Almost surely, 2^20866560 is an apocalyptic number.

20866560 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 20866560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41247360).

20866560 is an abundant number, since it is smaller than the sum of its proper divisors (61628160).

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

20866560 is a wasteful number, since it uses less digits than its factorization.

20866560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 20866560 is about 4567.9929947407. The cubic root of 20866560 is about 275.3068090903.

It can be divided in two parts, 2086 and 6560, that added together give a triangular number (8646 = T₁₃₁).

The spelling of 20866560 in words is "twenty million, eight hundred sixty-six thousand, five hundred sixty".