20666660 has 48 divisors (see below), whose sum is σ = 50768256. Its totient is φ = 6918912.

The previous prime is 20666651. The next prime is 20666669. The reversal of 20666660 is 6666602.

It is an interprime number because it is at equal distance from previous prime (20666651) and next prime (20666669).

It is a super-2 number, since 2×20666660² = 854221671111200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20666669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4304 + ... + 7736.

It is an arithmetic number, because the mean of its divisors is an integer number (1057672).

Almost surely, 2^20666660 is an apocalyptic number.

20666660 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 20666660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25384128).

20666660 is an abundant number, since it is smaller than the sum of its proper divisors (30101596).

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

20666660 is a wasteful number, since it uses less digits than its factorization.

20666660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3492 (or 3490 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 32.

The square root of 20666660 is about 4546.0598324263. The cubic root of 20666660 is about 274.4248475149.

It can be divided in two parts, 206 and 66660, that added together give a palindrome (66866).

The spelling of 20666660 in words is "twenty million, six hundred sixty-six thousand, six hundred sixty".