20666385 has 24 divisors (see below), whose sum is σ = 35950824. Its totient is φ = 10982400.

The previous prime is 20666377. The next prime is 20666389. The reversal of 20666385 is 58366602.

It can be written as a sum of positive squares in 4 ways, for example, as 199809 + 20466576 = 447^2 + 4524^2 .

It is not a de Polignac number, because 20666385 - 2³ = 20666377 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20666389) 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 23 ways as a sum of consecutive naturals, for example, 15235 + ... + 16535.

It is an arithmetic number, because the mean of its divisors is an integer number (1497951).

Almost surely, 2^20666385 is an apocalyptic number.

It is an amenable number.

20666385 is a deficient number, since it is larger than the sum of its proper divisors (15284439).

20666385 is a wasteful number, since it uses less digits than its factorization.

20666385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1665 (or 1662 counting only the distinct ones).

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

The square root of 20666385 is about 4546.0295863533. The cubic root of 20666385 is about 274.4236303021.

The spelling of 20666385 in words is "twenty million, six hundred sixty-six thousand, three hundred eighty-five".