21221211172 has 12 divisors (see below), whose sum is σ = 42442422400. Its totient is φ = 9094804776.

The previous prime is 21221211149. The next prime is 21221211173. The reversal of 21221211172 is 27111212212.

21221211172 is an admirable number.

It is a super-2 number, since 2×21221211172² (a number of 21 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21221211173) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 378950172 + ... + 378950227.

Almost surely, 2^21221211172 is an apocalyptic number.

It is an amenable number.

21221211172 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21221211172 is a wasteful number, since it uses less digits than its factorization.

21221211172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 757900410 (or 757900408 counting only the distinct ones).

The product of its digits is 224, while the sum is 22.

Adding to 21221211172 its reverse (27111212212), we get a palindrome (48332423384).

The spelling of 21221211172 in words is "twenty-one billion, two hundred twenty-one million, two hundred eleven thousand, one hundred seventy-two".