21004342 has 4 divisors (see below), whose sum is σ = 31506516. Its totient is φ = 10502170.

The previous prime is 21004331. The next prime is 21004351. The reversal of 21004342 is 24340012.

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 (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5251084 + ... + 5251087.

It is an arithmetic number, because the mean of its divisors is an integer number (7876629).

Almost surely, 2^21004342 is an apocalyptic number.

21004342 is a deficient number, since it is larger than the sum of its proper divisors (10502174).

21004342 is a wasteful number, since it uses less digits than its factorization.

21004342 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10502173.

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21004342 is about 4583.0494215097. The cubic root of 21004342 is about 275.9114310084.

Adding to 21004342 its reverse (24340012), we get a palindrome (45344354).

The spelling of 21004342 in words is "twenty-one million, four thousand, three hundred forty-two".