21791338 has 8 divisors (see below), whose sum is σ = 32717988. Its totient is φ = 10885344.

The previous prime is 21791333. The next prime is 21791353. The reversal of 21791338 is 83319712.

It can be written as a sum of positive squares in 2 ways, for example, as 21187609 + 603729 = 4603^2 + 777^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21791333) 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, 2181 + ... + 6952.

Almost surely, 2^21791338 is an apocalyptic number.

21791338 is a deficient number, since it is larger than the sum of its proper divisors (10926650).

21791338 is a wasteful number, since it uses less digits than its factorization.

21791338 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10328.

The product of its digits is 9072, while the sum is 34.

The square root of 21791338 is about 4668.1193215255. The cubic root of 21791338 is about 279.3152400010.

The spelling of 21791338 in words is "twenty-one million, seven hundred ninety-one thousand, three hundred thirty-eight".