20666388 has 12 divisors (see below), whose sum is σ = 48221600. Its totient is φ = 6888792.

The previous prime is 20666377. The next prime is 20666389. The reversal of 20666388 is 88366602.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 861088 + ... + 861111.

Almost surely, 2^20666388 is an apocalyptic number.

It is an amenable number.

20666388 is an abundant number, since it is smaller than the sum of its proper divisors (27555212).

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

20666388 is a wasteful number, since it uses less digits than its factorization.

20666388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1722206 (or 1722204 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 39.

The square root of 20666388 is about 4546.0299163116. The cubic root of 20666388 is about 274.4236435809.

The spelling of 20666388 in words is "twenty million, six hundred sixty-six thousand, three hundred eighty-eight".