18772181 has 2 divisors, whose sum is σ = 18772182. Its totient is φ = 18772180.

The previous prime is 18772177. The next prime is 18772183. The reversal of 18772181 is 18127781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16240900 + 2531281 = 4030^2 + 1591^2 .

It is a cyclic number.

It is not a de Polignac number, because 18772181 - 2² = 18772177 is a prime.

It is a super-2 number, since 2×18772181² = 704789558993522, which contains 22 as substring.

Together with 18772183, 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 (18772183) 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, 9386090 + 9386091.

It is an arithmetic number, because the mean of its divisors is an integer number (9386091).

Almost surely, 2^18772181 is an apocalyptic number.

It is an amenable number.

18772181 is a deficient number, since it is larger than the sum of its proper divisors (1).

18772181 is an equidigital number, since it uses as much as digits as its factorization.

18772181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6272, while the sum is 35.

The square root of 18772181 is about 4332.6875031555. The cubic root of 18772181 is about 265.7693602564.

The spelling of 18772181 in words is "eighteen million, seven hundred seventy-two thousand, one hundred eighty-one".