66161281 has 2 divisors, whose sum is σ = 66161282. Its totient is φ = 66161280.

The previous prime is 66161197. The next prime is 66161321. The reversal of 66161281 is 18216166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 44622400 + 21538881 = 6680^2 + 4641^2 .

It is a cyclic number.

It is not a de Polignac number, because 66161281 - 2⁷ = 66161153 is a prime.

It is a super-2 number, since 2×66161281² = 8754630207121922, which contains 22 as substring.

It is a Chen prime.

It is equal to p_3905086 and since 66161281 and 3905086 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 (66161581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33080640 + 33080641.

It is an arithmetic number, because the mean of its divisors is an integer number (33080641).

Almost surely, 2^66161281 is an apocalyptic number.

It is an amenable number.

66161281 is a deficient number, since it is larger than the sum of its proper divisors (1).

66161281 is an equidigital number, since it uses as much as digits as its factorization.

66161281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 31.

The square root of 66161281 is about 8133.9585073936. The cubic root of 66161281 is about 404.4529137024.

The spelling of 66161281 in words is "sixty-six million, one hundred sixty-one thousand, two hundred eighty-one".