129215981 has 2 divisors, whose sum is σ = 129215982. Its totient is φ = 129215980.

The previous prime is 129215939. The next prime is 129216011. The reversal of 129215981 is 189512921.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127893481 + 1322500 = 11309^2 + 1150^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129215981 is a prime.

It is a super-2 number, since 2×129215981² = 33393539491584722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129215921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64607990 + 64607991.

It is an arithmetic number, because the mean of its divisors is an integer number (64607991).

Almost surely, 2^129215981 is an apocalyptic number.

It is an amenable number.

129215981 is a deficient number, since it is larger than the sum of its proper divisors (1).

129215981 is an equidigital number, since it uses as much as digits as its factorization.

129215981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 38.

The square root of 129215981 is about 11367.3207485317. The cubic root of 129215981 is about 505.5592679964.

The spelling of 129215981 in words is "one hundred twenty-nine million, two hundred fifteen thousand, nine hundred eighty-one".