21055568 has 20 divisors (see below), whose sum is σ = 40878708. Its totient is φ = 10506240.

The previous prime is 21055561. The next prime is 21055579. The reversal of 21055568 is 86555012.

It can be written as a sum of positive squares in 2 ways, for example, as 15429184 + 5626384 = 3928^2 + 2372^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9230 + ... + 11282.

Almost surely, 2^21055568 is an apocalyptic number.

It is an amenable number.

21055568 is a deficient number, since it is larger than the sum of its proper divisors (19823140).

21055568 is a wasteful number, since it uses less digits than its factorization.

21055568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2702 (or 2696 counting only the distinct ones).

The product of its (nonzero) digits is 12000, while the sum is 32.

The square root of 21055568 is about 4588.6346553196. The cubic root of 21055568 is about 276.1355491851.

The spelling of 21055568 in words is "twenty-one million, fifty-five thousand, five hundred sixty-eight".