261329569 has 2 divisors, whose sum is σ = 261329570. Its totient is φ = 261329568.

The previous prime is 261329539. The next prime is 261329573. The reversal of 261329569 is 965923162.

261329569 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 245329569 + 16000000 = 15663^2 + 4000^2 .

It is a cyclic number.

It is not a de Polignac number, because 261329569 - 2¹⁵ = 261296801 is a prime.

It is a super-2 number, since 2×261329569² = 136586287267451522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261329539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130664784 + 130664785.

It is an arithmetic number, because the mean of its divisors is an integer number (130664785).

Almost surely, 2^261329569 is an apocalyptic number.

It is an amenable number.

261329569 is a deficient number, since it is larger than the sum of its proper divisors (1).

261329569 is an equidigital number, since it uses as much as digits as its factorization.

261329569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 174960, while the sum is 43.

The square root of 261329569 is about 16165.6911080226. The cubic root of 261329569 is about 639.3365267858.

The spelling of 261329569 in words is "two hundred sixty-one million, three hundred twenty-nine thousand, five hundred sixty-nine".