21004121121 has 12 divisors (see below), whose sum is σ = 29557047312. Its totient is φ = 13265760024.

The previous prime is 21004121101. The next prime is 21004121123. The reversal of 21004121121 is 12112140012.

It is not a de Polignac number, because 21004121121 - 2²⁷ = 20869903393 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21004121121.

It is not an unprimeable number, because it can be changed into a prime (21004121123) 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 11 ways as a sum of consecutive naturals, for example, 9696111 + ... + 9698276.

It is an arithmetic number, because the mean of its divisors is an integer number (2463087276).

Almost surely, 2^21004121121 is an apocalyptic number.

It is an amenable number.

21004121121 is a deficient number, since it is larger than the sum of its proper divisors (8552926191).

21004121121 is a wasteful number, since it uses less digits than its factorization.

21004121121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19394428 (or 19394409 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21004121121 its reverse (12112140012), we get a palindrome (33116261133).

The spelling of 21004121121 in words is "twenty-one billion, four million, one hundred twenty-one thousand, one hundred twenty-one".