261078817 has 2 divisors, whose sum is σ = 261078818. Its totient is φ = 261078816.

The previous prime is 261078787. The next prime is 261078827. The reversal of 261078817 is 718870162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135280161 + 125798656 = 11631^2 + 11216^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261078817 is a prime.

It is a super-2 number, since 2×261078817² = 136324297372238978, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 261078817.

It is not a weakly prime, because it can be changed into another prime (261078827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130539408 + 130539409.

It is an arithmetic number, because the mean of its divisors is an integer number (130539409).

Almost surely, 2^261078817 is an apocalyptic number.

It is an amenable number.

261078817 is a deficient number, since it is larger than the sum of its proper divisors (1).

261078817 is an equidigital number, since it uses as much as digits as its factorization.

261078817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 37632, while the sum is 40.

The square root of 261078817 is about 16157.9335621855. The cubic root of 261078817 is about 639.1319750952.

The spelling of 261078817 in words is "two hundred sixty-one million, seventy-eight thousand, eight hundred seventeen".