21109938 has 8 divisors (see below), whose sum is σ = 42219888. Its totient is φ = 7036644.

The previous prime is 21109927. The next prime is 21109939. The reversal of 21109938 is 83990112.

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

21109938 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21109899 and 21109908.

It is not an unprimeable number, because it can be changed into a prime (21109939) 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, 1759156 + ... + 1759167.

It is an arithmetic number, because the mean of its divisors is an integer number (5277486).

Almost surely, 2^21109938 is an apocalyptic number.

21109938 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21109938 is a wasteful number, since it uses less digits than its factorization.

21109938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3518328.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 21109938 is about 4594.5552559524. Note that the first 3 decimals coincide. The cubic root of 21109938 is about 276.3730253345.

The spelling of 21109938 in words is "twenty-one million, one hundred nine thousand, nine hundred thirty-eight".