129991747 has 4 divisors (see below), whose sum is σ = 131278896. Its totient is φ = 128704600.

The previous prime is 129991703. The next prime is 129991751. The reversal of 129991747 is 747199921.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129991747 is a prime.

It is a super-2 number, since 2×129991747² = 33795708576224018, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 129991747.

It is not an unprimeable number, because it can be changed into a prime (129991247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 643423 + ... + 643624.

It is an arithmetic number, because the mean of its divisors is an integer number (32819724).

Almost surely, 2^129991747 is an apocalyptic number.

129991747 is a deficient number, since it is larger than the sum of its proper divisors (1287149).

129991747 is a wasteful number, since it uses less digits than its factorization.

129991747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1287148.

The product of its digits is 285768, while the sum is 49.

The square root of 129991747 is about 11401.3923272555. The cubic root of 129991747 is about 506.5689816774.

The spelling of 129991747 in words is "one hundred twenty-nine million, nine hundred ninety-one thousand, seven hundred forty-seven".