21168447 has 8 divisors (see below), whose sum is σ = 28285440. Its totient is φ = 14081880.

The previous prime is 21168439. The next prime is 21168461. The reversal of 21168447 is 74486112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21168447 - 2³ = 21168439 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21168547) 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 in 7 ways as a sum of consecutive naturals, for example, 5929 + ... + 8802.

It is an arithmetic number, because the mean of its divisors is an integer number (3535680).

Almost surely, 2^21168447 is an apocalyptic number.

21168447 is a deficient number, since it is larger than the sum of its proper divisors (7116993).

21168447 is a wasteful number, since it uses less digits than its factorization.

21168447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15213.

The product of its digits is 10752, while the sum is 33.

The square root of 21168447 is about 4600.9180605614. The cubic root of 21168447 is about 276.6281246612.

The spelling of 21168447 in words is "twenty-one million, one hundred sixty-eight thousand, four hundred forty-seven".