21216212352123 has 16 divisors (see below), whose sum is σ = 28479735648000. Its totient is φ = 14048425967840.

The previous prime is 21216212352119. The next prime is 21216212352149. The reversal of 21216212352123 is 32125321261212.

It is a cyclic number.

It is not a de Polignac number, because 21216212352123 - 2² = 21216212352119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21216212352113) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6695818 + ... + 9341648.

It is an arithmetic number, because the mean of its divisors is an integer number (1779983478000).

Almost surely, 2^{21216212352123} is an apocalyptic number.

21216212352123 is a deficient number, since it is larger than the sum of its proper divisors (7263523295877).

21216212352123 is a wasteful number, since it uses less digits than its factorization.

21216212352123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2663922.

The product of its digits is 17280, while the sum is 33.

It can be divided in two parts, 2121621 and 2352123, that added together give a palindrome (4473744).

The spelling of 21216212352123 in words is "twenty-one trillion, two hundred sixteen billion, two hundred twelve million, three hundred fifty-two thousand, one hundred twenty-three".