20385666 has 72 divisors (see below), whose sum is σ = 53218620. Its totient is φ = 5616576.

The previous prime is 20385653. The next prime is 20385671. The reversal of 20385666 is 66658302.

It can be written as a sum of positive squares in 2 ways, for example, as 20385225 + 441 = 4515^2 + 21^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20385666.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 25180 + ... + 25976.

Almost surely, 2^20385666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20385666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26609310).

20385666 is an abundant number, since it is smaller than the sum of its proper divisors (32832954).

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

20385666 is a wasteful number, since it uses less digits than its factorization.

20385666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 848 (or 838 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 20385666 is about 4515.0488369452. The cubic root of 20385666 is about 273.1754296512.

The spelling of 20385666 in words is "twenty million, three hundred eighty-five thousand, six hundred sixty-six".