20406666 has 32 divisors (see below), whose sum is σ = 47134080. Its totient is φ = 5769216.

The previous prime is 20406641. The next prime is 20406667. The reversal of 20406666 is 66660402.

20406666 is a modest number, since divided by 6666 gives 2040 as remainder.

It is not an unprimeable number, because it can be changed into a prime (20406667) 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, 1570 + ... + 6578.

It is an arithmetic number, because the mean of its divisors is an integer number (1472940).

Almost surely, 2^20406666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20406666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23567040).

20406666 is an abundant number, since it is smaller than the sum of its proper divisors (26727414).

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

20406666 is a wasteful number, since it uses less digits than its factorization.

20406666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5118.

The product of its (nonzero) digits is 10368, while the sum is 30.

The square root of 20406666 is about 4517.3737945846. The cubic root of 20406666 is about 273.2692000369.

The spelling of 20406666 in words is "twenty million, four hundred six thousand, six hundred sixty-six".