21012320117 has 2 divisors, whose sum is σ = 21012320118. Its totient is φ = 21012320116.

The previous prime is 21012320107. The next prime is 21012320143. The reversal of 21012320117 is 71102321012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13696254961 + 7316065156 = 117031^2 + 85534^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012320117 - 2²⁶ = 20945211253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012320107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506160058 + 10506160059.

It is an arithmetic number, because the mean of its divisors is an integer number (10506160059).

Almost surely, 2^21012320117 is an apocalyptic number.

It is an amenable number.

21012320117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012320117 is an equidigital number, since it uses as much as digits as its factorization.

21012320117 is an evil number, because the sum of its binary digits is even.

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

Adding to 21012320117 its reverse (71102321012), we get a palindrome (92114641129).

The spelling of 21012320117 in words is "twenty-one billion, twelve million, three hundred twenty thousand, one hundred seventeen".