20909556 has 24 divisors (see below), whose sum is σ = 54210240. Its totient is φ = 6969816.

The previous prime is 20909533. The next prime is 20909563. The reversal of 20909556 is 65590902.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 20909556.

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, 96696 + ... + 96911.

It is an arithmetic number, because the mean of its divisors is an integer number (2258760).

Almost surely, 2^20909556 is an apocalyptic number.

It is an amenable number.

20909556 is an abundant number, since it is smaller than the sum of its proper divisors (33300684).

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

20909556 is a wasteful number, since it uses less digits than its factorization.

20909556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193620 (or 193612 counting only the distinct ones).

The product of its (nonzero) digits is 24300, while the sum is 36.

The square root of 20909556 is about 4572.6967972959. The cubic root of 20909556 is about 275.4957712490.

The spelling of 20909556 in words is "twenty million, nine hundred nine thousand, five hundred fifty-six".