71720002121 has 2 divisors, whose sum is σ = 71720002122. Its totient is φ = 71720002120.

The previous prime is 71720002093. The next prime is 71720002127. The reversal of 71720002121 is 12120002717.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37554176521 + 34165825600 = 193789^2 + 184840^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71720002121 is a prime.

It is not a weakly prime, because it can be changed into another prime (71720002127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35860001060 + 35860001061.

It is an arithmetic number, because the mean of its divisors is an integer number (35860001061).

Almost surely, 2^71720002121 is an apocalyptic number.

It is an amenable number.

71720002121 is a deficient number, since it is larger than the sum of its proper divisors (1).

71720002121 is an equidigital number, since it uses as much as digits as its factorization.

71720002121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 392, while the sum is 23.

Adding to 71720002121 its reverse (12120002717), we get a palindrome (83840004838).

The spelling of 71720002121 in words is "seventy-one billion, seven hundred twenty million, two thousand, one hundred twenty-one".