21000033121 has 4 divisors (see below), whose sum is σ = 21040186672. Its totient is φ = 20959879572.

The previous prime is 21000033107. The next prime is 21000033167. The reversal of 21000033121 is 12133000012.

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 a de Polignac number, because none of the positive numbers 2^k-21000033121 is a prime.

It is a super-3 number, since 3×21000033121³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000033191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20075991 + ... + 20077036.

It is an arithmetic number, because the mean of its divisors is an integer number (5260046668).

Almost surely, 2^21000033121 is an apocalyptic number.

It is an amenable number.

21000033121 is a deficient number, since it is larger than the sum of its proper divisors (40153551).

21000033121 is an equidigital number, since it uses as much as digits as its factorization.

21000033121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40153550.

The product of its (nonzero) digits is 36, while the sum is 13.

Adding to 21000033121 its reverse (12133000012), we get a palindrome (33133033133).

The spelling of 21000033121 in words is "twenty-one billion, thirty-three thousand, one hundred twenty-one".