261523613 has 6 divisors (see below), whose sum is σ = 283188474. Its totient is φ = 241406256.

The previous prime is 261523589. The next prime is 261523649. The reversal of 261523613 is 316325162.

It can be written as a sum of positive squares in 3 ways, for example, as 26759929 + 234763684 = 5173^2 + 15322^2 .

It is not a de Polignac number, because 261523613 - 2¹⁴ = 261507229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261523673) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 773570 + ... + 773907.

It is an arithmetic number, because the mean of its divisors is an integer number (47198079).

Almost surely, 2^261523613 is an apocalyptic number.

It is an amenable number.

261523613 is a deficient number, since it is larger than the sum of its proper divisors (21664861).

261523613 is a wasteful number, since it uses less digits than its factorization.

261523613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1547503 (or 1547490 counting only the distinct ones).

The product of its digits is 6480, while the sum is 29.

The square root of 261523613 is about 16171.6917173189. The cubic root of 261523613 is about 639.4947289675.

Adding to 261523613 its reverse (316325162), we get a palindrome (577848775).

The spelling of 261523613 in words is "two hundred sixty-one million, five hundred twenty-three thousand, six hundred thirteen".