21051442 has 4 divisors (see below), whose sum is σ = 31577166. Its totient is φ = 10525720.

The previous prime is 21051431. The next prime is 21051451. The reversal of 21051442 is 24415012.

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., 15673681 + 5377761 = 3959^2 + 2319^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5262859 + ... + 5262862.

Almost surely, 2^21051442 is an apocalyptic number.

21051442 is a deficient number, since it is larger than the sum of its proper divisors (10525724).

21051442 is a wasteful number, since it uses less digits than its factorization.

21051442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10525723.

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21051442 is about 4588.1850442196. The cubic root of 21051442 is about 276.1175110475.

Adding to 21051442 its reverse (24415012), we get a palindrome (45466454).

The spelling of 21051442 in words is "twenty-one million, fifty-one thousand, four hundred forty-two".