21231020117 has 2 divisors, whose sum is σ = 21231020118. Its totient is φ = 21231020116.

The previous prime is 21231020101. The next prime is 21231020123. The reversal of 21231020117 is 71102013212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16876867921 + 4354152196 = 129911^2 + 65986^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231020117 - 2⁴ = 21231020101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21231020017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615510058 + 10615510059.

It is an arithmetic number, because the mean of its divisors is an integer number (10615510059).

Almost surely, 2^21231020117 is an apocalyptic number.

It is an amenable number.

21231020117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231020117 is an equidigital number, since it uses as much as digits as its factorization.

21231020117 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 168, while the sum is 20.

Adding to 21231020117 its reverse (71102013212), we get a palindrome (92333033329).

The spelling of 21231020117 in words is "twenty-one billion, two hundred thirty-one million, twenty thousand, one hundred seventeen".