21749238 has 36 divisors (see below), whose sum is σ = 54819180. Its totient is φ = 6213816.

The previous prime is 21749219. The next prime is 21749249. The reversal of 21749238 is 83294712.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11448 + ... + 13211.

It is an arithmetic number, because the mean of its divisors is an integer number (1522755).

Almost surely, 2^21749238 is an apocalyptic number.

21749238 is an abundant number, since it is smaller than the sum of its proper divisors (33069942).

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

21749238 is a wasteful number, since it uses less digits than its factorization.

21749238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24681 (or 24671 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21749238 is about 4663.6078308537. The cubic root of 21749238 is about 279.1352487204.

It can be divided in two parts, 217 and 49238, that added together give a triangular number (49455 = T₃₁₄).

The spelling of 21749238 in words is "twenty-one million, seven hundred forty-nine thousand, two hundred thirty-eight".