21556016011272 has 128 divisors (see below), whose sum is σ = 57761803008000. Its totient is φ = 6683861733120.

The previous prime is 21556016011267. The next prime is 21556016011273. The reversal of 21556016011272 is 27211061065512.

It is a self number, because there is not a number n which added to its sum of digits gives 21556016011272.

It is not an unprimeable number, because it can be changed into a prime (21556016011273) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4867363 + ... + 8173325.

It is an arithmetic number, because the mean of its divisors is an integer number (451264086000).

Almost surely, 2^{21556016011272} 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 21556016011272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28880901504000).

21556016011272 is an abundant number, since it is smaller than the sum of its proper divisors (36205786996728).

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

21556016011272 is a wasteful number, since it uses less digits than its factorization.

21556016011272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3306251 (or 3306247 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 39.

Adding to 21556016011272 its reverse (27211061065512), we get a palindrome (48767077076784).

The spelling of 21556016011272 in words is "twenty-one trillion, five hundred fifty-six billion, sixteen million, eleven thousand, two hundred seventy-two".