161641993 has 2 divisors, whose sum is σ = 161641994. Its totient is φ = 161641992.

The previous prime is 161641981. The next prime is 161642003. The reversal of 161641993 is 399146161.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 102475129 + 59166864 = 10123^2 + 7692^2 .

It is a cyclic number.

It is not a de Polignac number, because 161641993 - 2⁹ = 161641481 is a prime.

It is a super-2 number, since 2×161641993² = 52256267802024098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161641913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80820996 + 80820997.

It is an arithmetic number, because the mean of its divisors is an integer number (80820997).

Almost surely, 2^161641993 is an apocalyptic number.

It is an amenable number.

161641993 is a deficient number, since it is larger than the sum of its proper divisors (1).

161641993 is an equidigital number, since it uses as much as digits as its factorization.

161641993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 40.

The square root of 161641993 is about 12713.8504395797. The cubic root of 161641993 is about 544.7343126049.

The spelling of 161641993 in words is "one hundred sixty-one million, six hundred forty-one thousand, nine hundred ninety-three".