20681788 has 12 divisors (see below), whose sum is σ = 36310960. Its totient is φ = 10307232.

The previous prime is 20681777. The next prime is 20681813. The reversal of 20681788 is 88718602.

It is a self number, because there is not a number n which added to its sum of digits gives 20681788.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7008 + ... + 9511.

Almost surely, 2^20681788 is an apocalyptic number.

It is an amenable number.

20681788 is a deficient number, since it is larger than the sum of its proper divisors (15629172).

20681788 is a wasteful number, since it uses less digits than its factorization.

20681788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16836 (or 16834 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 40.

The square root of 20681788 is about 4547.7233864869. The cubic root of 20681788 is about 274.4917908678.

The spelling of 20681788 in words is "twenty million, six hundred eighty-one thousand, seven hundred eighty-eight".