21791968 has 24 divisors (see below), whose sum is σ = 46803960. Its totient is φ = 9905280.

The previous prime is 21791921. The next prime is 21791969. The reversal of 21791968 is 86919712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21791969) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30603 + ... + 31306.

It is an arithmetic number, because the mean of its divisors is an integer number (1950165).

Almost surely, 2^21791968 is an apocalyptic number.

It is an amenable number.

21791968 is an abundant number, since it is smaller than the sum of its proper divisors (25011992).

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

21791968 is a wasteful number, since it uses less digits than its factorization.

21791968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61930 (or 61922 counting only the distinct ones).

The product of its digits is 54432, while the sum is 43.

The square root of 21791968 is about 4668.1868000327. The cubic root of 21791968 is about 279.3179316959.

The spelling of 21791968 in words is "twenty-one million, seven hundred ninety-one thousand, nine hundred sixty-eight".