21868656 has 20 divisors (see below), whose sum is σ = 56494152. Its totient is φ = 7289536.

The previous prime is 21868633. The next prime is 21868657. The reversal of 21868656 is 65686812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21868657) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 227751 + ... + 227846.

Almost surely, 2^21868656 is an apocalyptic number.

It is an amenable number.

21868656 is an abundant number, since it is smaller than the sum of its proper divisors (34625496).

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

21868656 is a wasteful number, since it uses less digits than its factorization.

21868656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455608 (or 455602 counting only the distinct ones).

The product of its digits is 138240, while the sum is 42.

The square root of 21868656 is about 4676.3934821612. The cubic root of 21868656 is about 279.6451968582.

The spelling of 21868656 in words is "twenty-one million, eight hundred sixty-eight thousand, six hundred fifty-six".