21031231121 has 2 divisors, whose sum is σ = 21031231122. Its totient is φ = 21031231120.

The previous prime is 21031231099. The next prime is 21031231147. The reversal of 21031231121 is 12113213012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11264850496 + 9766380625 = 106136^2 + 98825^2 .

It is a cyclic number.

It is not a de Polignac number, because 21031231121 - 2¹⁰ = 21031230097 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21031231121.

It is not a weakly prime, because it can be changed into another prime (21031231171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10515615560 + 10515615561.

It is an arithmetic number, because the mean of its divisors is an integer number (10515615561).

Almost surely, 2^21031231121 is an apocalyptic number.

It is an amenable number.

21031231121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21031231121 is an equidigital number, since it uses as much as digits as its factorization.

21031231121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21031231121 its reverse (12113213012), we get a palindrome (33144444133).

The spelling of 21031231121 in words is "twenty-one billion, thirty-one million, two hundred thirty-one thousand, one hundred twenty-one".