21238542 has 96 divisors (see below), whose sum is σ = 55429920. Its totient is φ = 5806080.

The previous prime is 21238519. The next prime is 21238543. The reversal of 21238542 is 24583212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21238543) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 75442 + ... + 75722.

It is an arithmetic number, because the mean of its divisors is an integer number (577395).

Almost surely, 2^21238542 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21238542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27714960).

21238542 is an abundant number, since it is smaller than the sum of its proper divisors (34191378).

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

21238542 is a wasteful number, since it uses less digits than its factorization.

21238542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338 (or 335 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 21238542 is about 4608.5292664797. The cubic root of 21238542 is about 276.9331208252.

The spelling of 21238542 in words is "twenty-one million, two hundred thirty-eight thousand, five hundred forty-two".