21120121321 has 4 divisors (see below), whose sum is σ = 22744746052. Its totient is φ = 19495496592.

The previous prime is 21120121313. The next prime is 21120121357. The reversal of 21120121321 is 12312102112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13319698921 + 7800422400 = 115411^2 + 88320^2 .

It is not a de Polignac number, because 21120121321 - 2³ = 21120121313 is a prime.

It is a super-2 number, since 2×21120121321² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120121295 and 21120121304.

It is not an unprimeable number, because it can be changed into a prime (21120121021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 812312346 + ... + 812312371.

It is an arithmetic number, because the mean of its divisors is an integer number (5686186513).

Almost surely, 2^21120121321 is an apocalyptic number.

It is an amenable number.

21120121321 is a deficient number, since it is larger than the sum of its proper divisors (1624624731).

21120121321 is a wasteful number, since it uses less digits than its factorization.

21120121321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1624624730.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21120121321 its reverse (12312102112), we get a palindrome (33432223433).

The spelling of 21120121321 in words is "twenty-one billion, one hundred twenty million, one hundred twenty-one thousand, three hundred twenty-one".