21236442 has 32 divisors (see below), whose sum is σ = 43848000. Its totient is φ = 6852480.

The previous prime is 21236431. The next prime is 21236447. The reversal of 21236442 is 24463212.

It is not an unprimeable number, because it can be changed into a prime (21236447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42309 + ... + 42807.

It is an arithmetic number, because the mean of its divisors is an integer number (1370250).

Almost surely, 2^21236442 is an apocalyptic number.

21236442 is an abundant number, since it is smaller than the sum of its proper divisors (22611558).

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

21236442 is a wasteful number, since it uses less digits than its factorization.

21236442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 718.

The product of its digits is 2304, while the sum is 24.

The square root of 21236442 is about 4608.3014224332. The cubic root of 21236442 is about 276.9239931000.

Adding to 21236442 its reverse (24463212), we get a palindrome (45699654).

The spelling of 21236442 in words is "twenty-one million, two hundred thirty-six thousand, four hundred forty-two".