21722205172 has 12 divisors (see below), whose sum is σ = 38047898980. Its totient is φ = 10851376896.

The previous prime is 21722205157. The next prime is 21722205173. The reversal of 21722205172 is 27150222712.

It can be written as a sum of positive squares in 2 ways, for example, as 1746905616 + 19975299556 = 41796^2 + 141334^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722205173) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2426397 + ... + 2435332.

Almost surely, 2^21722205172 is an apocalyptic number.

It is an amenable number.

21722205172 is a deficient number, since it is larger than the sum of its proper divisors (16325693808).

21722205172 is a wasteful number, since it uses less digits than its factorization.

21722205172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4862850 (or 4862848 counting only the distinct ones).

The product of its (nonzero) digits is 7840, while the sum is 31.

Adding to 21722205172 its reverse (27150222712), we get a palindrome (48872427884).

The spelling of 21722205172 in words is "twenty-one billion, seven hundred twenty-two million, two hundred five thousand, one hundred seventy-two".