667938181 has 2 divisors, whose sum is σ = 667938182. Its totient is φ = 667938180.

The previous prime is 667938163. The next prime is 667938199. The reversal of 667938181 is 181839766.

It is a balanced prime because it is at equal distance from previous prime (667938163) and next prime (667938199).

It can be written as a sum of positive squares in only one way, i.e., 509404900 + 158533281 = 22570^2 + 12591^2 .

It is a cyclic number.

It is not a de Polignac number, because 667938181 - 2⁷ = 667938053 is a prime.

It is a super-2 number, since 2×667938181² = 892282827275177522, which contains 22 as substring.

It is the 25845-th Hogben number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667938281) by changing a digit.

It is a nontrivial repunit in base 25844.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333969090 + 333969091.

It is an arithmetic number, because the mean of its divisors is an integer number (333969091).

Almost surely, 2^667938181 is an apocalyptic number.

It is an amenable number.

667938181 is a deficient number, since it is larger than the sum of its proper divisors (1).

667938181 is an equidigital number, since it uses as much as digits as its factorization.

667938181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 49.

The square root of 667938181 is about 25844.5000145099. The cubic root of 667938181 is about 874.1354970611.

The spelling of 667938181 in words is "six hundred sixty-seven million, nine hundred thirty-eight thousand, one hundred eighty-one".