261520517 has 2 divisors, whose sum is σ = 261520518. Its totient is φ = 261520516.

The previous prime is 261520513. The next prime is 261520543. The reversal of 261520517 is 715025162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 229552801 + 31967716 = 15151^2 + 5654^2 .

It is a cyclic number.

It is not a de Polignac number, because 261520517 - 2² = 261520513 is a prime.

It is a super-3 number, since 3×261520517³ (a number of 26 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 261520517.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261520513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130760258 + 130760259.

It is an arithmetic number, because the mean of its divisors is an integer number (130760259).

Almost surely, 2^261520517 is an apocalyptic number.

It is an amenable number.

261520517 is a deficient number, since it is larger than the sum of its proper divisors (1).

261520517 is an equidigital number, since it uses as much as digits as its factorization.

261520517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 261520517 is about 16171.5959942116. The cubic root of 261520517 is about 639.4922054433.

Adding to 261520517 its reverse (715025162), we get a palindrome (976545679).

It can be divided in two parts, 2615 and 20517, that added together give a palindrome (23132).

The spelling of 261520517 in words is "two hundred sixty-one million, five hundred twenty thousand, five hundred seventeen".