129997891 has 2 divisors, whose sum is σ = 129997892. Its totient is φ = 129997890.

The previous prime is 129997877. The next prime is 129997913. The reversal of 129997891 is 198799921.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129997891 is a prime.

It is not a weakly prime, because it can be changed into another prime (129997801) 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, 64998945 + 64998946.

It is an arithmetic number, because the mean of its divisors is an integer number (64998946).

Almost surely, 2^129997891 is an apocalyptic number.

129997891 is a deficient number, since it is larger than the sum of its proper divisors (1).

129997891 is an equidigital number, since it uses as much as digits as its factorization.

129997891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 734832, while the sum is 55.

The square root of 129997891 is about 11401.6617648481. The cubic root of 129997891 is about 506.5769624681.

The spelling of 129997891 in words is "one hundred twenty-nine million, nine hundred ninety-seven thousand, eight hundred ninety-one".