181604861 has 2 divisors, whose sum is σ = 181604862. Its totient is φ = 181604860.

The previous prime is 181604833. The next prime is 181604887. The reversal of 181604861 is 168406181.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166152100 + 15452761 = 12890^2 + 3931^2 .

It is a cyclic number.

It is not a de Polignac number, because 181604861 - 2¹⁸ = 181342717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181604461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90802430 + 90802431.

It is an arithmetic number, because the mean of its divisors is an integer number (90802431).

Almost surely, 2^181604861 is an apocalyptic number.

It is an amenable number.

181604861 is a deficient number, since it is larger than the sum of its proper divisors (1).

181604861 is an equidigital number, since it uses as much as digits as its factorization.

181604861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 181604861 is about 13476.0847800836. The cubic root of 181604861 is about 566.2946904027.

The spelling of 181604861 in words is "one hundred eighty-one million, six hundred four thousand, eight hundred sixty-one".