21712221216 has 144 divisors (see below), whose sum is σ = 70650425664. Its totient is φ = 6195958272.

The previous prime is 21712221199. The next prime is 21712221217. The reversal of 21712221216 is 61212221712.

It is a happy number.

21712221216 is a `hidden beast` number, since 217 + 12 + 221 + 216 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a self number, because there is not a number n which added to its sum of digits gives 21712221216.

It is not an unprimeable number, because it can be changed into a prime (21712221217) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1774030 + ... + 1786226.

It is an arithmetic number, because the mean of its divisors is an integer number (490627956).

Almost surely, 2^21712221216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21712221216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35325212832).

21712221216 is an abundant number, since it is smaller than the sum of its proper divisors (48938204448).

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

21712221216 is a wasteful number, since it uses less digits than its factorization.

21712221216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13103 (or 13092 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

Adding to 21712221216 its reverse (61212221712), we get a palindrome (82924442928).

The spelling of 21712221216 in words is "twenty-one billion, seven hundred twelve million, two hundred twenty-one thousand, two hundred sixteen".