21705122 has 8 divisors (see below), whose sum is σ = 32587500. Its totient is φ = 10842624.

The previous prime is 21705091. The next prime is 21705133. The reversal of 21705122 is 22150712.

It can be written as a sum of positive squares in 2 ways, for example, as 20967241 + 737881 = 4579^2 + 859^2 .

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

It is a super-2 number, since 2×21705122² = 942224642069768, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21705094 and 21705103.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 1847 + ... + 6842.

Almost surely, 2^21705122 is an apocalyptic number.

21705122 is a deficient number, since it is larger than the sum of its proper divisors (10882378).

21705122 is a wasteful number, since it uses less digits than its factorization.

21705122 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9940.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 21705122 is about 4658.8756154248. The cubic root of 21705122 is about 278.9463889831.

Adding to 21705122 its reverse (22150712), we get a palindrome (43855834).

The spelling of 21705122 in words is "twenty-one million, seven hundred five thousand, one hundred twenty-two".