21287163 has 8 divisors (see below), whose sum is σ = 29876800. Its totient is φ = 13444488.

The previous prime is 21287143. The next prime is 21287209. The reversal of 21287163 is 36178212.

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

It is not a de Polignac number, because 21287163 - 2¹⁴ = 21270779 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21287163.

It is not an unprimeable number, because it can be changed into a prime (21287143) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 186673 + ... + 186786.

It is an arithmetic number, because the mean of its divisors is an integer number (3734600).

Almost surely, 2^21287163 is an apocalyptic number.

21287163 is a deficient number, since it is larger than the sum of its proper divisors (8589637).

21287163 is a wasteful number, since it uses less digits than its factorization.

21287163 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373481.

The product of its digits is 4032, while the sum is 30.

The square root of 21287163 is about 4613.8013611338. The cubic root of 21287163 is about 277.1442857196.

The spelling of 21287163 in words is "twenty-one million, two hundred eighty-seven thousand, one hundred sixty-three".