21109942 has 8 divisors (see below), whose sum is σ = 36188496. Its totient is φ = 9047112.

The previous prime is 21109939. The next prime is 21109973. The reversal of 21109942 is 24990112.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21109942.

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, 753913 + ... + 753940.

It is an arithmetic number, because the mean of its divisors is an integer number (4523562).

Almost surely, 2^21109942 is an apocalyptic number.

21109942 is a deficient number, since it is larger than the sum of its proper divisors (15078554).

21109942 is a wasteful number, since it uses less digits than its factorization.

21109942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1507862.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 21109942 is about 4594.5556912502. Note that the first 3 decimals coincide. The cubic root of 21109942 is about 276.3730427906.

The spelling of 21109942 in words is "twenty-one million, one hundred nine thousand, nine hundred forty-two".