20905656 has 32 divisors (see below), whose sum is σ = 53952000. Its totient is φ = 6743520.

The previous prime is 20905637. The next prime is 20905657. The reversal of 20905656 is 65650902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20905657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13306 + ... + 14793.

It is an arithmetic number, because the mean of its divisors is an integer number (1686000).

Almost surely, 2^20905656 is an apocalyptic number.

It is an amenable number.

20905656 is an abundant number, since it is smaller than the sum of its proper divisors (33046344).

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

20905656 is a wasteful number, since it uses less digits than its factorization.

20905656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28139 (or 28135 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 33.

The square root of 20905656 is about 4572.2703332152. The cubic root of 20905656 is about 275.4786419148.

The spelling of 20905656 in words is "twenty million, nine hundred five thousand, six hundred fifty-six".