129447891 has 12 divisors (see below), whose sum is σ = 187218720. Its totient is φ = 86188560.

The previous prime is 129447869. The next prime is 129447949. The reversal of 129447891 is 198744921.

It is a happy number.

129447891 is a `hidden beast` number, since 1 + 2 + 94 + 478 + 91 = 666.

It is not a de Polignac number, because 129447891 - 2⁷ = 129447763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (129447821) 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 in 11 ways as a sum of consecutive naturals, for example, 1371 + ... + 16148.

It is an arithmetic number, because the mean of its divisors is an integer number (15601560).

Almost surely, 2^129447891 is an apocalyptic number.

129447891 is a deficient number, since it is larger than the sum of its proper divisors (57770829).

129447891 is a wasteful number, since it uses less digits than its factorization.

129447891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18346 (or 18343 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The square root of 129447891 is about 11377.5169083592. The cubic root of 129447891 is about 505.8615375700.

The spelling of 129447891 in words is "one hundred twenty-nine million, four hundred forty-seven thousand, eight hundred ninety-one".