129905869 has 4 divisors (see below), whose sum is σ = 136743040. Its totient is φ = 123068700.

The previous prime is 129905851. The next prime is 129905879. The reversal of 129905869 is 968509921.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-129905869 is a prime.

It is a super-2 number, since 2×129905869² = 33751069601290322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129905879) 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 in 3 ways as a sum of consecutive naturals, for example, 3418557 + ... + 3418594.

It is an arithmetic number, because the mean of its divisors is an integer number (34185760).

Almost surely, 2^129905869 is an apocalyptic number.

129905869 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

129905869 is a deficient number, since it is larger than the sum of its proper divisors (6837171).

129905869 is an equidigital number, since it uses as much as digits as its factorization.

129905869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6837170.

The product of its (nonzero) digits is 349920, while the sum is 49.

The square root of 129905869 is about 11397.6255860596. The cubic root of 129905869 is about 506.4574035310.

The spelling of 129905869 in words is "one hundred twenty-nine million, nine hundred five thousand, eight hundred sixty-nine".