21125542 has 4 divisors (see below), whose sum is σ = 31688316. Its totient is φ = 10562770.

The previous prime is 21125521. The next prime is 21125551. The reversal of 21125542 is 24552112.

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

It is a congruent number.

It is an unprimeable number.

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, 5281384 + ... + 5281387.

It is an arithmetic number, because the mean of its divisors is an integer number (7922079).

Almost surely, 2^21125542 is an apocalyptic number.

21125542 is a deficient number, since it is larger than the sum of its proper divisors (10562774).

21125542 is a wasteful number, since it uses less digits than its factorization.

21125542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10562773.

The product of its digits is 800, while the sum is 22.

The square root of 21125542 is about 4596.2530391614. The cubic root of 21125542 is about 276.4411048420.

Adding to 21125542 its reverse (24552112), we get a palindrome (45677654).

The spelling of 21125542 in words is "twenty-one million, one hundred twenty-five thousand, five hundred forty-two".