20815956 has 144 divisors (see below), whose sum is σ = 65729664. Its totient is φ = 5419008.

The previous prime is 20815933. The next prime is 20815961. The reversal of 20815956 is 65951802.

It is a happy number.

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 20815956.

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 184156 + ... + 184268.

It is an arithmetic number, because the mean of its divisors is an integer number (456456).

Almost surely, 2^20815956 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20815956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32864832).

20815956 is an abundant number, since it is smaller than the sum of its proper divisors (44913708).

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

20815956 is a wasteful number, since it uses less digits than its factorization.

20815956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190 (or 185 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 20815956 is about 4562.4506572674. The cubic root of 20815956 is about 275.0840778729.

The spelling of 20815956 in words is "twenty million, eight hundred fifteen thousand, nine hundred fifty-six".