163165721 has 2 divisors, whose sum is σ = 163165722. Its totient is φ = 163165720.

The previous prime is 163165669. The next prime is 163165753. The reversal of 163165721 is 127561361.

It is an a-pointer prime, because the next prime (163165753) can be obtained adding 163165721 to its sum of digits (32).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 162282121 + 883600 = 12739^2 + 940^2 .

It is a cyclic number.

It is not a de Polignac number, because 163165721 - 2¹⁰ = 163164697 is a prime.

It is equal to p_9141854 and since 163165721 and 9141854 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 (163165781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81582860 + 81582861.

It is an arithmetic number, because the mean of its divisors is an integer number (81582861).

Almost surely, 2^163165721 is an apocalyptic number.

It is an amenable number.

163165721 is a deficient number, since it is larger than the sum of its proper divisors (1).

163165721 is an equidigital number, since it uses as much as digits as its factorization.

163165721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7560, while the sum is 32.

The square root of 163165721 is about 12773.6338212742. The cubic root of 163165721 is about 546.4406192047.

The spelling of 163165721 in words is "one hundred sixty-three million, one hundred sixty-five thousand, seven hundred twenty-one".