129720863981 has 2 divisors, whose sum is σ = 129720863982. Its totient is φ = 129720863980.

The previous prime is 129720863977. The next prime is 129720864061. The reversal of 129720863981 is 189368027921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 129233779081 + 487084900 = 359491^2 + 22070^2 .

It is an emirp because it is prime and its reverse (189368027921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 129720863981 - 2² = 129720863977 is a prime.

It is a super-2 number, since 2×129720863981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129720863281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64860431990 + 64860431991.

It is an arithmetic number, because the mean of its divisors is an integer number (64860431991).

Almost surely, 2^129720863981 is an apocalyptic number.

It is an amenable number.

129720863981 is a deficient number, since it is larger than the sum of its proper divisors (1).

129720863981 is an equidigital number, since it uses as much as digits as its factorization.

129720863981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2612736, while the sum is 56.

The spelling of 129720863981 in words is "one hundred twenty-nine billion, seven hundred twenty million, eight hundred sixty-three thousand, nine hundred eighty-one".