165661393 has 2 divisors, whose sum is σ = 165661394. Its totient is φ = 165661392.

The previous prime is 165661381. The next prime is 165661409. The reversal of 165661393 is 393166561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 124277904 + 41383489 = 11148^2 + 6433^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165661393 is a prime.

It is equal to p_9273748 and since 165661393 and 9273748 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (165661343) 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, 82830696 + 82830697.

It is an arithmetic number, because the mean of its divisors is an integer number (82830697).

Almost surely, 2^165661393 is an apocalyptic number.

It is an amenable number.

165661393 is a deficient number, since it is larger than the sum of its proper divisors (1).

165661393 is an equidigital number, since it uses as much as digits as its factorization.

165661393 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 87480, while the sum is 40.

The square root of 165661393 is about 12870.9515188272. The cubic root of 165661393 is about 549.2125292634.

The spelling of 165661393 in words is "one hundred sixty-five million, six hundred sixty-one thousand, three hundred ninety-three".