21107838 has 32 divisors (see below), whose sum is σ = 43840512. Its totient is φ = 6768000.

The previous prime is 21107791. The next prime is 21107839. The reversal of 21107838 is 83870112.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21107839) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 52438 + ... + 52838.

It is an arithmetic number, because the mean of its divisors is an integer number (1370016).

Almost surely, 2^21107838 is an apocalyptic number.

21107838 is an abundant number, since it is smaller than the sum of its proper divisors (22732674).

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

21107838 is a wasteful number, since it uses less digits than its factorization.

21107838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 720.

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 21107838 is about 4594.3267189002. The cubic root of 21107838 is about 276.3638605736.

It can be divided in two parts, 21107 and 838, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21107838 in words is "twenty-one million, one hundred seven thousand, eight hundred thirty-eight".