181820939 has 2 divisors, whose sum is σ = 181820940. Its totient is φ = 181820938.

The previous prime is 181820929. The next prime is 181820941. The reversal of 181820939 is 939028181.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181820939 is a prime.

Together with 181820941, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 181820896 and 181820905.

It is not a weakly prime, because it can be changed into another prime (181820929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90910469 + 90910470.

It is an arithmetic number, because the mean of its divisors is an integer number (90910470).

Almost surely, 2^181820939 is an apocalyptic number.

181820939 is a deficient number, since it is larger than the sum of its proper divisors (1).

181820939 is an equidigital number, since it uses as much as digits as its factorization.

181820939 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104, while the sum is 41.

The square root of 181820939 is about 13484.0994879154. The cubic root of 181820939 is about 566.5191985739.

The spelling of 181820939 in words is "one hundred eighty-one million, eight hundred twenty thousand, nine hundred thirty-nine".