18406181 has 2 divisors, whose sum is σ = 18406182. Its totient is φ = 18406180.

The previous prime is 18406169. The next prime is 18406183. The reversal of 18406181 is 18160481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17355556 + 1050625 = 4166^2 + 1025^2 .

It is an emirp because it is prime and its reverse (18160481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18406181 - 2¹⁰ = 18405157 is a prime.

It is a super-2 number, since 2×18406181² = 677574998009522, which contains 22 as substring.

Together with 18406183, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18406183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9203090 + 9203091.

It is an arithmetic number, because the mean of its divisors is an integer number (9203091).

Almost surely, 2^18406181 is an apocalyptic number.

It is an amenable number.

18406181 is a deficient number, since it is larger than the sum of its proper divisors (1).

18406181 is an equidigital number, since it uses as much as digits as its factorization.

18406181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1536, while the sum is 29.

The square root of 18406181 is about 4290.2425339367. The cubic root of 18406181 is about 264.0307824911.

The spelling of 18406181 in words is "eighteen million, four hundred six thousand, one hundred eighty-one".