21568671 has 12 divisors (see below), whose sum is σ = 31879848. Its totient is φ = 14044464.

The previous prime is 21568643. The next prime is 21568691. The reversal of 21568671 is 17686512.

21568671 is a `hidden beast` number, since 21 + 568 + 6 + 71 = 666.

It is not a de Polignac number, because 21568671 - 2⁵ = 21568639 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21568621) 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 11 ways as a sum of consecutive naturals, for example, 27480 + ... + 28253.

It is an arithmetic number, because the mean of its divisors is an integer number (2656654).

Almost surely, 2^21568671 is an apocalyptic number.

21568671 is a deficient number, since it is larger than the sum of its proper divisors (10311177).

21568671 is a wasteful number, since it uses less digits than its factorization.

21568671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55782 (or 55779 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21568671 is about 4644.2083286605. The cubic root of 21568671 is about 278.3606201112.

It can be divided in two parts, 215 and 68671, that added together give a palindrome (68886).

The spelling of 21568671 in words is "twenty-one million, five hundred sixty-eight thousand, six hundred seventy-one".