181972129 has 4 divisors (see below), whose sum is σ = 188247060. Its totient is φ = 175697200.

The previous prime is 181972123. The next prime is 181972157. The reversal of 181972129 is 921279181.

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

It can be written as a sum of positive squares in 2 ways, for example, as 34398225 + 147573904 = 5865^2 + 12148^2 .

It is a cyclic number.

It is not a de Polignac number, because 181972129 - 2¹¹ = 181970081 is a prime.

It is a super-2 number, since 2×181972129² = 66227711465585282, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 181972091 and 181972100.

It is not an unprimeable number, because it can be changed into a prime (181972123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3137422 + ... + 3137479.

It is an arithmetic number, because the mean of its divisors is an integer number (47061765).

Almost surely, 2^181972129 is an apocalyptic number.

It is an amenable number.

181972129 is a deficient number, since it is larger than the sum of its proper divisors (6274931).

181972129 is an equidigital number, since it uses as much as digits as its factorization.

181972129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6274930.

The product of its digits is 18144, while the sum is 40.

The square root of 181972129 is about 13489.7045556973. The cubic root of 181972129 is about 566.6761814242.

The spelling of 181972129 in words is "one hundred eighty-one million, nine hundred seventy-two thousand, one hundred twenty-nine".