18646861 has 2 divisors, whose sum is σ = 18646862. Its totient is φ = 18646860.

The previous prime is 18646829. The next prime is 18646867. The reversal of 18646861 is 16864681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18224361 + 422500 = 4269^2 + 650^2 .

It is a cyclic number.

It is not a de Polignac number, because 18646861 - 2⁵ = 18646829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18646867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9323430 + 9323431.

It is an arithmetic number, because the mean of its divisors is an integer number (9323431).

Almost surely, 2^18646861 is an apocalyptic number.

It is an amenable number.

18646861 is a deficient number, since it is larger than the sum of its proper divisors (1).

18646861 is an equidigital number, since it uses as much as digits as its factorization.

18646861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 40.

The square root of 18646861 is about 4318.2011301004. The cubic root of 18646861 is about 265.1766284201.

The spelling of 18646861 in words is "eighteen million, six hundred forty-six thousand, eight hundred sixty-one".