21600215172 has 18 divisors (see below), whose sum is σ = 54600543998. Its totient is φ = 7200071712.

The previous prime is 21600215167. The next prime is 21600215177. The reversal of 21600215172 is 27151200612.

21600215172 is a `hidden beast` number, since 2 + 1 + 600 + 2 + 1 + 51 + 7 + 2 = 666.

It is an interprime number because it is at equal distance from previous prime (21600215167) and next prime (21600215177).

It can be written as a sum of positive squares in only one way, i.e., 13676366916 + 7923848256 = 116946^2 + 89016^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is not an unprimeable number, because it can be changed into a prime (21600215177) 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 5 ways as a sum of consecutive naturals, for example, 300002953 + ... + 300003024.

Almost surely, 2^21600215172 is an apocalyptic number.

It is an amenable number.

21600215172 is an abundant number, since it is smaller than the sum of its proper divisors (33000328826).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21600215172 is a wasteful number, since it uses less digits than its factorization.

21600215172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600005987 (or 600005982 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

Adding to 21600215172 its reverse (27151200612), we get a palindrome (48751415784).

The spelling of 21600215172 in words is "twenty-one billion, six hundred million, two hundred fifteen thousand, one hundred seventy-two".