20989688 has 8 divisors (see below), whose sum is σ = 39355680. Its totient is φ = 10494840.

The previous prime is 20989651. The next prime is 20989711. The reversal of 20989688 is 88698902.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1311848 + ... + 1311863.

It is an arithmetic number, because the mean of its divisors is an integer number (4919460).

Almost surely, 2^20989688 is an apocalyptic number.

It is an amenable number.

20989688 is a deficient number, since it is larger than the sum of its proper divisors (18365992).

20989688 is a wasteful number, since it uses less digits than its factorization.

20989688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2623717 (or 2623713 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 50.

The square root of 20989688 is about 4581.4504253566. The cubic root of 20989688 is about 275.8472514728.

The spelling of 20989688 in words is "twenty million, nine hundred eighty-nine thousand, six hundred eighty-eight".