20121243917 has 2 divisors, whose sum is σ = 20121243918. Its totient is φ = 20121243916.

The previous prime is 20121243899. The next prime is 20121244027. The reversal of 20121243917 is 71934212102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13006490116 + 7114753801 = 114046^2 + 84349^2 .

It is a cyclic number.

It is not a de Polignac number, because 20121243917 - 2²⁶ = 20054135053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20121243017) 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 as a sum of consecutive naturals, namely, 10060621958 + 10060621959.

It is an arithmetic number, because the mean of its divisors is an integer number (10060621959).

Almost surely, 2^20121243917 is an apocalyptic number.

It is an amenable number.

20121243917 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121243917 is an equidigital number, since it uses as much as digits as its factorization.

20121243917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 32.

The spelling of 20121243917 in words is "twenty billion, one hundred twenty-one million, two hundred forty-three thousand, nine hundred seventeen".