21705163 has 8 divisors (see below), whose sum is σ = 23162000. Its totient is φ = 20279808.

The previous prime is 21705161. The next prime is 21705191. The reversal of 21705163 is 36150712.

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

It is a cyclic number.

It is not a de Polignac number, because 21705163 - 2¹ = 21705161 is a prime.

It is a super-2 number, since 2×21705163² = 942228201713138, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21705161) 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, 6438 + ... + 9211.

It is an arithmetic number, because the mean of its divisors is an integer number (2895250).

Almost surely, 2^21705163 is an apocalyptic number.

21705163 is a deficient number, since it is larger than the sum of its proper divisors (1456837).

21705163 is a wasteful number, since it uses less digits than its factorization.

21705163 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15741.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21705163 is about 4658.8800156261. The cubic root of 21705163 is about 278.9465646220.

Adding to 21705163 its reverse (36150712), we get a palindrome (57855875).

The spelling of 21705163 in words is "twenty-one million, seven hundred five thousand, one hundred sixty-three".