21438238 has 4 divisors (see below), whose sum is σ = 32157360. Its totient is φ = 10719118.

The previous prime is 21438217. The next prime is 21438239. The reversal of 21438238 is 83283412.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21438239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5359558 + ... + 5359561.

It is an arithmetic number, because the mean of its divisors is an integer number (8039340).

Almost surely, 2^21438238 is an apocalyptic number.

21438238 is a deficient number, since it is larger than the sum of its proper divisors (10719122).

21438238 is a wasteful number, since it uses less digits than its factorization.

21438238 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10719121.

The product of its digits is 9216, while the sum is 31.

The square root of 21438238 is about 4630.1444901860. The cubic root of 21438238 is about 277.7983718183.

The spelling of 21438238 in words is "twenty-one million, four hundred thirty-eight thousand, two hundred thirty-eight".