66161521 has 2 divisors, whose sum is σ = 66161522. Its totient is φ = 66161520.

The previous prime is 66161519. The next prime is 66161531. The reversal of 66161521 is 12516166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59213025 + 6948496 = 7695^2 + 2636^2 .

It is a cyclic number.

It is not a de Polignac number, because 66161521 - 2¹ = 66161519 is a prime.

It is a super-2 number, since 2×66161521² = 8754693722066882, which contains 22 as substring.

Together with 66161519, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66161521.

It is not a weakly prime, because it can be changed into another prime (66161531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33080760 + 33080761.

It is an arithmetic number, because the mean of its divisors is an integer number (33080761).

Almost surely, 2^66161521 is an apocalyptic number.

It is an amenable number.

66161521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66161521 is an equidigital number, since it uses as much as digits as its factorization.

66161521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 28.

The square root of 66161521 is about 8133.9732603445. The cubic root of 66161521 is about 404.4534027527.

Adding to 66161521 its reverse (12516166), we get a palindrome (78677687).

The spelling of 66161521 in words is "sixty-six million, one hundred sixty-one thousand, five hundred twenty-one".