21131021121 has 12 divisors (see below), whose sum is σ = 32774645232. Its totient is φ = 12074869128.

The previous prime is 21131021059. The next prime is 21131021141. The reversal of 21131021121 is 12112013112.

It is not a de Polignac number, because 21131021121 - 2¹¹ = 21131019073 is a prime.

It is a super-2 number, since 2×21131021121² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21131021121.

It is not an unprimeable number, because it can be changed into a prime (21131021141) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71874075 + ... + 71874368.

It is an arithmetic number, because the mean of its divisors is an integer number (2731220436).

Almost surely, 2^21131021121 is an apocalyptic number.

21131021121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21131021121 is a deficient number, since it is larger than the sum of its proper divisors (11643624111).

21131021121 is a wasteful number, since it uses less digits than its factorization.

21131021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143748460 (or 143748453 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21131021121 its reverse (12112013112), we get a palindrome (33243034233).

The spelling of 21131021121 in words is "twenty-one billion, one hundred thirty-one million, twenty-one thousand, one hundred twenty-one".