21042103042 has 4 divisors (see below), whose sum is σ = 31563154566. Its totient is φ = 10521051520.

The previous prime is 21042103031. The next prime is 21042103057. The reversal of 21042103042 is 24030124012.

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., 15893897041 + 5148206001 = 126071^2 + 71751^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5260525759 + ... + 5260525762.

Almost surely, 2^21042103042 is an apocalyptic number.

21042103042 is a deficient number, since it is larger than the sum of its proper divisors (10521051524).

21042103042 is a wasteful number, since it uses less digits than its factorization.

21042103042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10521051523.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21042103042 its reverse (24030124012), we get a palindrome (45072227054).

The spelling of 21042103042 in words is "twenty-one billion, forty-two million, one hundred three thousand, forty-two".