21131121012 has 12 divisors (see below), whose sum is σ = 49305949056. Its totient is φ = 7043707000.

The previous prime is 21131121001. The next prime is 21131121019. The reversal of 21131121012 is 21012113112.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21131120982 and 21131121000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131121019) 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, 880463364 + ... + 880463387.

It is an arithmetic number, because the mean of its divisors is an integer number (4108829088).

Almost surely, 2^21131121012 is an apocalyptic number.

It is an amenable number.

21131121012 is an abundant number, since it is smaller than the sum of its proper divisors (28174828044).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21131121012 is a wasteful number, since it uses less digits than its factorization.

21131121012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1760926758 (or 1760926756 counting only the distinct ones).

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

Adding to 21131121012 its reverse (21012113112), we get a palindrome (42143234124).

The spelling of 21131121012 in words is "twenty-one billion, one hundred thirty-one million, one hundred twenty-one thousand, twelve".