21668942 has 8 divisors (see below), whose sum is σ = 32691816. Its totient is φ = 10771672.

The previous prime is 21668929. The next prime is 21668957. The reversal of 21668942 is 24986612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21668896 and 21668905.

It is a congruent number.

It is an unprimeable number.

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, 30968 + ... + 31659.

It is an arithmetic number, because the mean of its divisors is an integer number (4086477).

Almost surely, 2^21668942 is an apocalyptic number.

21668942 is a deficient number, since it is larger than the sum of its proper divisors (11022874).

21668942 is a wasteful number, since it uses less digits than its factorization.

21668942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62802.

The product of its digits is 41472, while the sum is 38.

The square root of 21668942 is about 4654.9910848465. The cubic root of 21668942 is about 278.7913120214.

The spelling of 21668942 in words is "twenty-one million, six hundred sixty-eight thousand, nine hundred forty-two".