129691 has 4 divisors (see below), whose sum is σ = 132192. Its totient is φ = 127192.

The previous prime is 129671. The next prime is 129707. The reversal of 129691 is 196921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196921 = 191 ⋅1031.

It is a cyclic number.

It is not a de Polignac number, because 129691 - 2¹¹ = 127643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129631) 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, 1171 + ... + 1276.

It is an arithmetic number, because the mean of its divisors is an integer number (33048).

2¹²⁹⁶⁹¹ is an apocalyptic number.

129691 is a deficient number, since it is larger than the sum of its proper divisors (2501).

129691 is an equidigital number, since it uses as much as digits as its factorization.

129691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2500.

The product of its digits is 972, while the sum is 28.

The square root of 129691 is about 360.1263667104. The cubic root of 129691 is about 50.6178016489.

It can be divided in two parts, 129 and 691, that added together give a triangular number (820 = T₄₀).

The spelling of 129691 in words is "one hundred twenty-nine thousand, six hundred ninety-one".