21921168 has 40 divisors (see below), whose sum is σ = 58164928. Its totient is φ = 7108992.

The previous prime is 21921167. The next prime is 21921169. The reversal of 21921168 is 86112912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21921167) and next prime (21921169).

It is not an unprimeable number, because it can be changed into a prime (21921167) 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 7 ways as a sum of consecutive naturals, for example, 4396 + ... + 7947.

Almost surely, 2^21921168 is an apocalyptic number.

It is an amenable number.

21921168 is an abundant number, since it is smaller than the sum of its proper divisors (36243760).

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

21921168 is a wasteful number, since it uses less digits than its factorization.

21921168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12391 (or 12385 counting only the distinct ones).

The product of its digits is 1728, while the sum is 30.

The square root of 21921168 is about 4682.0046988443. The cubic root of 21921168 is about 279.8688501446.

The spelling of 21921168 in words is "twenty-one million, nine hundred twenty-one thousand, one hundred sixty-eight".