20121121021 has 4 divisors (see below), whose sum is σ = 20589054112. Its totient is φ = 19653187932.

The previous prime is 20121120983. The next prime is 20121121057. The reversal of 20121121021 is 12012112102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20121121021 - 2⁷ = 20121120893 is a prime.

It is a super-2 number, since 2×20121121021² (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 = 20121120992 and 20121121010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121121061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 233966481 + ... + 233966566.

It is an arithmetic number, because the mean of its divisors is an integer number (5147263528).

Almost surely, 2^20121121021 is an apocalyptic number.

It is an amenable number.

20121121021 is a deficient number, since it is larger than the sum of its proper divisors (467933091).

20121121021 is an equidigital number, since it uses as much as digits as its factorization.

20121121021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 467933090.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 20121121021 its reverse (12012112102), we get a palindrome (32133233123).

The spelling of 20121121021 in words is "twenty billion, one hundred twenty-one million, one hundred twenty-one thousand, twenty-one".