161521 has 2 divisors, whose sum is σ = 161522. Its totient is φ = 161520.

The previous prime is 161507. The next prime is 161527. The reversal of 161521 is 125161.

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., 160000 + 1521 = 400^2 + 39^2 .

It is a cyclic number.

It is not a de Polignac number, because 161521 - 2⁹ = 161009 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 161495 and 161504.

It is not a weakly prime, because it can be changed into another prime (161527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80760 + 80761.

It is an arithmetic number, because the mean of its divisors is an integer number (80761).

2¹⁶¹⁵²¹ is an apocalyptic number.

It is an amenable number.

161521 is a deficient number, since it is larger than the sum of its proper divisors (1).

161521 is an equidigital number, since it uses as much as digits as its factorization.

161521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60, while the sum is 16.

The square root of 161521 is about 401.8967529105. The cubic root of 161521 is about 54.4598363010.

Adding to 161521 its reverse (125161), we get a palindrome (286682).

It can be divided in two parts, 16 and 1521, that multiplied together give a square (24336 = 156²).

The spelling of 161521 in words is "one hundred sixty-one thousand, five hundred twenty-one".