181620961 has 2 divisors, whose sum is σ = 181620962. Its totient is φ = 181620960.

The previous prime is 181620953. The next prime is 181620977. The reversal of 181620961 is 169026181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 100620961 + 81000000 = 10031^2 + 9000^2 .

It is a cyclic number.

It is not a de Polignac number, because 181620961 - 2³ = 181620953 is a prime.

It is not a weakly prime, because it can be changed into another prime (181630961) 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 as a sum of consecutive naturals, namely, 90810480 + 90810481.

It is an arithmetic number, because the mean of its divisors is an integer number (90810481).

Almost surely, 2^181620961 is an apocalyptic number.

It is an amenable number.

181620961 is a deficient number, since it is larger than the sum of its proper divisors (1).

181620961 is an equidigital number, since it uses as much as digits as its factorization.

181620961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 181620961 is about 13476.6821213532. The cubic root of 181620961 is about 566.3114246741.

The spelling of 181620961 in words is "one hundred eighty-one million, six hundred twenty thousand, nine hundred sixty-one".