129971981 has 2 divisors, whose sum is σ = 129971982. Its totient is φ = 129971980.

The previous prime is 129971969. The next prime is 129971993. The reversal of 129971981 is 189179921.

It is a balanced prime because it is at equal distance from previous prime (129971969) and next prime (129971993).

It can be written as a sum of positive squares in only one way, i.e., 67798756 + 62173225 = 8234^2 + 7885^2 .

It is a cyclic number.

It is not a de Polignac number, because 129971981 - 2⁶ = 129971917 is a prime.

It is a super-2 number, since 2×129971981² = 33785431690128722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129976981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64985990 + 64985991.

It is an arithmetic number, because the mean of its divisors is an integer number (64985991).

Almost surely, 2^129971981 is an apocalyptic number.

It is an amenable number.

129971981 is a deficient number, since it is larger than the sum of its proper divisors (1).

129971981 is an equidigital number, since it uses as much as digits as its factorization.

129971981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81648, while the sum is 47.

The square root of 129971981 is about 11400.5254703457. The cubic root of 129971981 is about 506.5433047908.

The spelling of 129971981 in words is "one hundred twenty-nine million, nine hundred seventy-one thousand, nine hundred eighty-one".