21132842 has 4 divisors (see below), whose sum is σ = 31699266. Its totient is φ = 10566420.

The previous prime is 21132841. The next prime is 21132847. The reversal of 21132842 is 24823112.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 19175641 + 1957201 = 4379^2 + 1399^2 .

It is not an unprimeable number, because it can be changed into a prime (21132841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5283209 + ... + 5283212.

Almost surely, 2^21132842 is an apocalyptic number.

21132842 is a deficient number, since it is larger than the sum of its proper divisors (10566424).

21132842 is a wasteful number, since it uses less digits than its factorization.

21132842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10566423.

The product of its digits is 768, while the sum is 23.

The square root of 21132842 is about 4597.0470956909. The cubic root of 21132842 is about 276.4729428838.

Adding to 21132842 its reverse (24823112), we get a palindrome (45955954).

The spelling of 21132842 in words is "twenty-one million, one hundred thirty-two thousand, eight hundred forty-two".