20989638 has 16 divisors (see below), whose sum is σ = 46643760. Its totient is φ = 6996528.

The previous prime is 20989627. The next prime is 20989651. The reversal of 20989638 is 83698902.

20989638 is a `hidden beast` number, since 2 + 0 + 9 + 8 + 9 + 638 = 666.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20989593 and 20989602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 194295 + ... + 194402.

It is an arithmetic number, because the mean of its divisors is an integer number (2915235).

Almost surely, 2^20989638 is an apocalyptic number.

20989638 is an abundant number, since it is smaller than the sum of its proper divisors (25654122).

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

20989638 is a wasteful number, since it uses less digits than its factorization.

20989638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388708 (or 388702 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 20989638 is about 4581.4449685661. Note that the first 3 decimals coincide. The cubic root of 20989638 is about 275.8470324387.

The spelling of 20989638 in words is "twenty million, nine hundred eighty-nine thousand, six hundred thirty-eight".