20785664 has 20 divisors (see below), whose sum is σ = 41531754. Its totient is φ = 10392576.

The previous prime is 20785631. The next prime is 20785669. The reversal of 20785664 is 46658702.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 11833600 + 8952064 = 3440^2 + 2992^2 .

It is not an unprimeable number, because it can be changed into a prime (20785669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19787 + ... + 20810.

Almost surely, 2^20785664 is an apocalyptic number.

It is an amenable number.

20785664 is a deficient number, since it is larger than the sum of its proper divisors (20746090).

20785664 is an frugal number, since it uses more digits than its factorization.

20785664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40615 (or 40599 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 38.

The square root of 20785664 is about 4559.1297415187. The cubic root of 20785664 is about 274.9505762419.

The spelling of 20785664 in words is "twenty million, seven hundred eighty-five thousand, six hundred sixty-four".