641561281 has 2 divisors, whose sum is σ = 641561282. Its totient is φ = 641561280.

The previous prime is 641561269. The next prime is 641561293. The reversal of 641561281 is 182165146.

641561281 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (641561269) and next prime (641561293).

It can be written as a sum of positive squares in only one way, i.e., 327031056 + 314530225 = 18084^2 + 17735^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-641561281 is a prime.

It is a super-2 number, since 2×641561281² = 823201754556721922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (641561881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320780640 + 320780641.

It is an arithmetic number, because the mean of its divisors is an integer number (320780641).

Almost surely, 2^641561281 is an apocalyptic number.

641561281 is the 11328-th centered decagonal number.

It is an amenable number.

641561281 is a deficient number, since it is larger than the sum of its proper divisors (1).

641561281 is an equidigital number, since it uses as much as digits as its factorization.

641561281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 34.

The square root of 641561281 is about 25329.0600101938. The cubic root of 641561281 is about 862.4740731827.

The spelling of 641561281 in words is "six hundred forty-one million, five hundred sixty-one thousand, two hundred eighty-one".