20689664 has 18 divisors (see below), whose sum is σ = 41299020. Its totient is φ = 10344704.

The previous prime is 20689661. The next prime is 20689699. The reversal of 20689664 is 46698602.

It is not an unprimeable number, because it can be changed into a prime (20689661) 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 as a sum of consecutive naturals, namely, 40154 + ... + 40665.

It is an arithmetic number, because the mean of its divisors is an integer number (2294390).

Almost surely, 2^20689664 is an apocalyptic number.

It is an amenable number.

20689664 is a deficient number, since it is larger than the sum of its proper divisors (20609356).

20689664 is an frugal number, since it uses more digits than its factorization.

20689664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80835 (or 80821 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 41.

The square root of 20689664 is about 4548.5892318388. The cubic root of 20689664 is about 274.5266302632.

The spelling of 20689664 in words is "twenty million, six hundred eighty-nine thousand, six hundred sixty-four".