21984479715121 has 45 divisors (see below), whose sum is σ = 28193782105433. Its totient is φ = 17128794134760.

The previous prime is 21984479715097. The next prime is 21984479715137. The reversal of 21984479715121 is 12151797448912.

The square root of 21984479715121 is 4688761.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21984479715121 - 2¹³ = 21984479706929 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21984479715121.

It is not an unprimeable number, because it can be changed into a prime (21984479715181) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 2527237830 + ... + 2527246528.

Almost surely, 2^{21984479715121} is an apocalyptic number.

21984479715121 is the 4688761-st square number.

21984479715121 is the 2344381-st centered octagonal number.

It is an amenable number.

21984479715121 is a deficient number, since it is larger than the sum of its proper divisors (6209302390312).

21984479715121 is an frugal number, since it uses more digits than its factorization.

21984479715121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17448 (or 8717 counting only the distinct ones).

The product of its digits is 10160640, while the sum is 61.

The spelling of 21984479715121 in words is "twenty-one trillion, nine hundred eighty-four billion, four hundred seventy-nine million, seven hundred fifteen thousand, one hundred twenty-one".