181918397 has 2 divisors, whose sum is σ = 181918398. Its totient is φ = 181918396.

The previous prime is 181918391. The next prime is 181918427. The reversal of 181918397 is 793819181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 108284836 + 73633561 = 10406^2 + 8581^2 .

It is a cyclic number.

It is not a de Polignac number, because 181918397 - 2¹² = 181914301 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181918391) by changing a digit.

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, 90959198 + 90959199.

It is an arithmetic number, because the mean of its divisors is an integer number (90959199).

Almost surely, 2^181918397 is an apocalyptic number.

It is an amenable number.

181918397 is a deficient number, since it is larger than the sum of its proper divisors (1).

181918397 is an equidigital number, since it uses as much as digits as its factorization.

181918397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 47.

The square root of 181918397 is about 13487.7128157446. The cubic root of 181918397 is about 566.6204006440.

The spelling of 181918397 in words is "one hundred eighty-one million, nine hundred eighteen thousand, three hundred ninety-seven".