261776729 has 2 divisors, whose sum is σ = 261776730. Its totient is φ = 261776728.

The previous prime is 261776653. The next prime is 261776743. The reversal of 261776729 is 927677162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 225150025 + 36626704 = 15005^2 + 6052^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261776729 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261776789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130888364 + 130888365.

It is an arithmetic number, because the mean of its divisors is an integer number (130888365).

Almost surely, 2^261776729 is an apocalyptic number.

It is an amenable number.

261776729 is a deficient number, since it is larger than the sum of its proper divisors (1).

261776729 is an equidigital number, since it uses as much as digits as its factorization.

261776729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 444528, while the sum is 47.

The square root of 261776729 is about 16179.5157220480. The cubic root of 261776729 is about 639.7009744038.

The spelling of 261776729 in words is "two hundred sixty-one million, seven hundred seventy-six thousand, seven hundred twenty-nine".