999997181 has 2 divisors, whose sum is σ = 999997182. Its totient is φ = 999997180.

The previous prime is 999997133. The next prime is 999997237. The reversal of 999997181 is 181799999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 879656281 + 120340900 = 29659^2 + 10970^2 .

It is a cyclic number.

It is not a de Polignac number, because 999997181 - 2¹⁴ = 999980797 is a prime.

It is a super-2 number, since 2×999997181² = 1999988724015893522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999997081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499998590 + 499998591.

It is an arithmetic number, because the mean of its divisors is an integer number (499998591).

Almost surely, 2^999997181 is an apocalyptic number.

It is an amenable number.

999997181 is a deficient number, since it is larger than the sum of its proper divisors (1).

999997181 is an equidigital number, since it uses as much as digits as its factorization.

999997181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3306744, while the sum is 62.

The square root of 999997181 is about 31622.7320293488. The cubic root of 999997181 is about 999.9990603325. Note that the first 3 decimals are identical.

The spelling of 999997181 in words is "nine hundred ninety-nine million, nine hundred ninety-seven thousand, one hundred eighty-one".