65561281 has 2 divisors, whose sum is σ = 65561282. Its totient is φ = 65561280.

The previous prime is 65561269. The next prime is 65561297. The reversal of 65561281 is 18216556.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64641600 + 919681 = 8040^2 + 959^2 .

It is a cyclic number.

It is not a de Polignac number, because 65561281 - 2⁹ = 65560769 is a prime.

It is a super-3 number, since 3×65561281³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is equal to p_3871753 and since 65561281 and 3871753 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 (65561581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32780640 + 32780641.

It is an arithmetic number, because the mean of its divisors is an integer number (32780641).

Almost surely, 2^65561281 is an apocalyptic number.

It is an amenable number.

65561281 is a deficient number, since it is larger than the sum of its proper divisors (1).

65561281 is an equidigital number, since it uses as much as digits as its factorization.

65561281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 34.

The square root of 65561281 is about 8096.9920958341. The cubic root of 65561281 is about 403.2265718538.

The spelling of 65561281 in words is "sixty-five million, five hundred sixty-one thousand, two hundred eighty-one".