21216223234225 has 24 divisors (see below), whose sum is σ = 28208256341760. Its totient is φ = 15772358334720.

The previous prime is 21216223234163. The next prime is 21216223234273. The reversal of 21216223234225 is 52243232261212.

It is not a de Polignac number, because 21216223234225 - 2³¹ = 21214075750577 is a prime.

It is a super-4 number, since 4×21216223234225⁴ (a number of 54 digits) contains 4444 as substring. Note that it is a super-d number also for d = 3, 2.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 315919117 + ... + 315986266.

It is an arithmetic number, because the mean of its divisors is an integer number (1175344014240).

Almost surely, 2^{21216223234225} is an apocalyptic number.

21216223234225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21216223234225 is a deficient number, since it is larger than the sum of its proper divisors (6992033107535).

21216223234225 is a wasteful number, since it uses less digits than its factorization.

21216223234225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 631905489 (or 631905484 counting only the distinct ones).

The product of its digits is 138240, while the sum is 37.

Adding to 21216223234225 its reverse (52243232261212), we get a palindrome (73459455495437).

The spelling of 21216223234225 in words is "twenty-one trillion, two hundred sixteen billion, two hundred twenty-three million, two hundred thirty-four thousand, two hundred twenty-five".