161393993 has 2 divisors, whose sum is σ = 161393994. Its totient is φ = 161393992.

The previous prime is 161393989. The next prime is 161394017. The reversal of 161393993 is 399393161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 147792649 + 13601344 = 12157^2 + 3688^2 .

It is an emirp because it is prime and its reverse (399393161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161393993 - 2² = 161393989 is a prime.

It is not a weakly prime, because it can be changed into another prime (161393293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80696996 + 80696997.

It is an arithmetic number, because the mean of its divisors is an integer number (80696997).

Almost surely, 2^161393993 is an apocalyptic number.

It is an amenable number.

161393993 is a deficient number, since it is larger than the sum of its proper divisors (1).

161393993 is an equidigital number, since it uses as much as digits as its factorization.

161393993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 118098, while the sum is 44.

The square root of 161393993 is about 12704.0935528671. The cubic root of 161393993 is about 544.4555829350.

The spelling of 161393993 in words is "one hundred sixty-one million, three hundred ninety-three thousand, nine hundred ninety-three".