21731056 has 20 divisors (see below), whose sum is σ = 42184800. Its totient is φ = 10844672.

The previous prime is 21731053. The next prime is 21731069. The reversal of 21731056 is 65013712.

It is a self number, because there is not a number n which added to its sum of digits gives 21731056.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21731051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10560 + ... + 12448.

It is an arithmetic number, because the mean of its divisors is an integer number (2109240).

Almost surely, 2^21731056 is an apocalyptic number.

It is an amenable number.

21731056 is a deficient number, since it is larger than the sum of its proper divisors (20453744).

21731056 is a wasteful number, since it uses less digits than its factorization.

21731056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2616 (or 2610 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21731056 is about 4661.6580741191. The cubic root of 21731056 is about 279.0574428984.

Adding to 21731056 its reverse (65013712), we get a palindrome (86744768).

The spelling of 21731056 in words is "twenty-one million, seven hundred thirty-one thousand, fifty-six".