261566782069 has 2 divisors, whose sum is σ = 261566782070. Its totient is φ = 261566782068.

The previous prime is 261566781997. The next prime is 261566782097. The reversal of 261566782069 is 960287665162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 194776582225 + 66790199844 = 441335^2 + 258438^2 .

It is a cyclic number.

It is not a de Polignac number, because 261566782069 - 2⁷ = 261566781941 is a prime.

It is a super-2 number, since 2×261566782069² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261566782669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130783391034 + 130783391035.

It is an arithmetic number, because the mean of its divisors is an integer number (130783391035).

Almost surely, 2^261566782069 is an apocalyptic number.

It is an amenable number.

261566782069 is a deficient number, since it is larger than the sum of its proper divisors (1).

261566782069 is an equidigital number, since it uses as much as digits as its factorization.

261566782069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13063680, while the sum is 58.

The spelling of 261566782069 in words is "two hundred sixty-one billion, five hundred sixty-six million, seven hundred eighty-two thousand, sixty-nine".