165521641 has 2 divisors, whose sum is σ = 165521642. Its totient is φ = 165521640.

The previous prime is 165521591. The next prime is 165521659. The reversal of 165521641 is 146125561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152769600 + 12752041 = 12360^2 + 3571^2 .

It is a cyclic number.

It is not a de Polignac number, because 165521641 - 2¹¹ = 165519593 is a prime.

It is not a weakly prime, because it can be changed into another prime (165522641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82760820 + 82760821.

It is an arithmetic number, because the mean of its divisors is an integer number (82760821).

Almost surely, 2^165521641 is an apocalyptic number.

It is an amenable number.

165521641 is a deficient number, since it is larger than the sum of its proper divisors (1).

165521641 is an equidigital number, since it uses as much as digits as its factorization.

165521641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7200, while the sum is 31.

The square root of 165521641 is about 12865.5214041251. The cubic root of 165521641 is about 549.0580471977.

The spelling of 165521641 in words is "one hundred sixty-five million, five hundred twenty-one thousand, six hundred forty-one".