181581949 has 2 divisors, whose sum is σ = 181581950. Its totient is φ = 181581948.

The previous prime is 181581943. The next prime is 181581971. The reversal of 181581949 is 949185181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 166874724 + 14707225 = 12918^2 + 3835^2 .

It is a cyclic number.

It is not a de Polignac number, because 181581949 - 2¹⁹ = 181057661 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 181581899 and 181581908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181581943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90790974 + 90790975.

It is an arithmetic number, because the mean of its divisors is an integer number (90790975).

Almost surely, 2^181581949 is an apocalyptic number.

It is an amenable number.

181581949 is a deficient number, since it is larger than the sum of its proper divisors (1).

181581949 is an equidigital number, since it uses as much as digits as its factorization.

181581949 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 46.

The square root of 181581949 is about 13475.2346547287. The cubic root of 181581949 is about 566.2708740622.

The spelling of 181581949 in words is "one hundred eighty-one million, five hundred eighty-one thousand, nine hundred forty-nine".