261788981015489 has 2 divisors, whose sum is σ = 261788981015490. Its totient is φ = 261788981015488.

The previous prime is 261788981015431. The next prime is 261788981015491. The reversal of 261788981015489 is 984510189887162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 240724782334864 + 21064198680625 = 15515308^2 + 4589575^2 .

It is a cyclic number.

It is not a de Polignac number, because 261788981015489 - 2¹⁶ = 261788980949953 is a prime.

It is a super-2 number, since 2×261788981015489² (a number of 30 digits) contains 22 as substring.

Together with 261788981015491, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261788981015189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130894490507744 + 130894490507745.

It is an arithmetic number, because the mean of its divisors is an integer number (130894490507745).

Almost surely, 2^{261788981015489} is an apocalyptic number.

It is an amenable number.

261788981015489 is a deficient number, since it is larger than the sum of its proper divisors (1).

261788981015489 is an equidigital number, since it uses as much as digits as its factorization.

261788981015489 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 557383680, while the sum is 77.

The spelling of 261788981015489 in words is "two hundred sixty-one trillion, seven hundred eighty-eight billion, nine hundred eighty-one million, fifteen thousand, four hundred eighty-nine".