21050656 has 48 divisors (see below), whose sum is σ = 45843840. Its totient is φ = 9434880.

The previous prime is 21050629. The next prime is 21050677. The reversal of 21050656 is 65605012.

It is a self number, because there is not a number n which added to its sum of digits gives 21050656.

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, 27430 + ... + 28186.

It is an arithmetic number, because the mean of its divisors is an integer number (955080).

Almost surely, 2^21050656 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 21050656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22921920).

21050656 is an abundant number, since it is smaller than the sum of its proper divisors (24793184).

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

21050656 is a wasteful number, since it uses less digits than its factorization.

21050656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 857 (or 849 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 21050656 is about 4588.0993886358. The cubic root of 21050656 is about 276.1140745281.

Adding to 21050656 its reverse (65605012), we get a palindrome (86655668).

The spelling of 21050656 in words is "twenty-one million, fifty thousand, six hundred fifty-six".