20509956 has 48 divisors (see below), whose sum is σ = 56306880. Its totient is φ = 6433920.

The previous prime is 20509933. The next prime is 20509967. The reversal of 20509956 is 65990502.

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 20509956.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3750 + ... + 7421.

It is an arithmetic number, because the mean of its divisors is an integer number (1173060).

Almost surely, 2^20509956 is an apocalyptic number.

It is an amenable number.

20509956 is an abundant number, since it is smaller than the sum of its proper divisors (35796924).

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

20509956 is a wasteful number, since it uses less digits than its factorization.

20509956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11201 (or 11193 counting only the distinct ones).

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

The square root of 20509956 is about 4528.7918918846. The cubic root of 20509956 is about 273.7294824180.

The spelling of 20509956 in words is "twenty million, five hundred nine thousand, nine hundred fifty-six".