21205325121 has 16 divisors (see below), whose sum is σ = 28679712768. Its totient is φ = 13934018000.

The previous prime is 21205325077. The next prime is 21205325137. The reversal of 21205325121 is 12152350212.

It is a cyclic number.

It is not a de Polignac number, because 21205325121 - 2⁷ = 21205324993 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21205325091 and 21205325100.

It is not an unprimeable number, because it can be changed into a prime (21205325221) 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, 936880 + ... + 959246.

It is an arithmetic number, because the mean of its divisors is an integer number (1792482048).

Almost surely, 2^21205325121 is an apocalyptic number.

It is an amenable number.

21205325121 is a deficient number, since it is larger than the sum of its proper divisors (7474387647).

21205325121 is a wasteful number, since it uses less digits than its factorization.

21205325121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26892.

The product of its (nonzero) digits is 1200, while the sum is 24.

Adding to 21205325121 its reverse (12152350212), we get a palindrome (33357675333).

The spelling of 21205325121 in words is "twenty-one billion, two hundred five million, three hundred twenty-five thousand, one hundred twenty-one".