20666560 has 112 divisors (see below), whose sum is σ = 54315360. Its totient is φ = 7454720.

The previous prime is 20666557. The next prime is 20666561. The reversal of 20666560 is 6566602.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (20666561) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 157695 + ... + 157825.

Almost surely, 2^20666560 is an apocalyptic number.

20666560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

20666560 is the 3712-nd pentagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20666560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27157680).

20666560 is an abundant number, since it is smaller than the sum of its proper divisors (33648800).

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

20666560 is a wasteful number, since it uses less digits than its factorization.

20666560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194 (or 184 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 20666560 is about 4546.0488338776. The cubic root of 20666560 is about 274.4244048933.

It can be divided in two parts, 206 and 66560, that added together give a palindrome (66766).

The spelling of 20666560 in words is "twenty million, six hundred sixty-six thousand, five hundred sixty".