1218172393 has 2 divisors, whose sum is σ = 1218172394. Its totient is φ = 1218172392.

The previous prime is 1218172387. The next prime is 1218172411. The reversal of 1218172393 is 3932718121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1156204009 + 61968384 = 34003^2 + 7872^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1218172393 is a prime.

It is not a weakly prime, because it can be changed into another prime (1218172313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 609086196 + 609086197.

It is an arithmetic number, because the mean of its divisors is an integer number (609086197).

Almost surely, 2^1218172393 is an apocalyptic number.

It is an amenable number.

1218172393 is a deficient number, since it is larger than the sum of its proper divisors (1).

1218172393 is an equidigital number, since it uses as much as digits as its factorization.

1218172393 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 37.

The square root of 1218172393 is about 34902.3264697355. The cubic root of 1218172393 is about 1067.9958972592.

The spelling of 1218172393 in words is "one billion, two hundred eighteen million, one hundred seventy-two thousand, three hundred ninety-three".