21989238 has 8 divisors (see below), whose sum is σ = 43978488. Its totient is φ = 7329744.

The previous prime is 21989237. The next prime is 21989269. The reversal of 21989238 is 83298912.

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

21989238 is an admirable number.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21989238.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21989237) 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, 1832431 + ... + 1832442.

It is an arithmetic number, because the mean of its divisors is an integer number (5497311).

Almost surely, 2^21989238 is an apocalyptic number.

21989238 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.

21989238 is a wasteful number, since it uses less digits than its factorization.

21989238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3664878.

The product of its digits is 62208, while the sum is 42.

The square root of 21989238 is about 4689.2683864330. The cubic root of 21989238 is about 280.1582353901.

The spelling of 21989238 in words is "twenty-one million, nine hundred eighty-nine thousand, two hundred thirty-eight".