129181931 has 4 divisors (see below), whose sum is σ = 135981000. Its totient is φ = 122382864.

The previous prime is 129181891. The next prime is 129181951. The reversal of 129181931 is 139181921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 139181921 = 41 ⋅3394681.

It is a cyclic number.

It is not a de Polignac number, because 129181931 - 2¹⁰ = 129180907 is a prime.

It is a super-2 number, since 2×129181931² = 33375942593777522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 129181891 and 129181900.

It is not an unprimeable number, because it can be changed into a prime (129181951) 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, 3399506 + ... + 3399543.

It is an arithmetic number, because the mean of its divisors is an integer number (33995250).

Almost surely, 2^129181931 is an apocalyptic number.

129181931 is a deficient number, since it is larger than the sum of its proper divisors (6799069).

129181931 is an equidigital number, since it uses as much as digits as its factorization.

129181931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6799068.

The product of its digits is 3888, while the sum is 35.

The square root of 129181931 is about 11365.8229354499. The cubic root of 129181931 is about 505.5148570672.

The spelling of 129181931 in words is "one hundred twenty-nine million, one hundred eighty-one thousand, nine hundred thirty-one".