261541613 has 4 divisors (see below), whose sum is σ = 261830880. Its totient is φ = 261252348.

The previous prime is 261541607. The next prime is 261541627. The reversal of 261541613 is 316145162.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 316145162 = 2 ⋅158072581.

It is a cyclic number.

It is not a de Polignac number, because 261541613 - 2⁴ = 261541597 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 (261541663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 143273 + ... + 145086.

It is an arithmetic number, because the mean of its divisors is an integer number (65457720).

Almost surely, 2^261541613 is an apocalyptic number.

It is an amenable number.

261541613 is a deficient number, since it is larger than the sum of its proper divisors (289267).

261541613 is an equidigital number, since it uses as much as digits as its factorization.

261541613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289266.

The product of its digits is 4320, while the sum is 29.

The square root of 261541613 is about 16172.2482357896. The cubic root of 261541613 is about 639.5094002253.

Adding to 261541613 its reverse (316145162), we get a palindrome (577686775).

The spelling of 261541613 in words is "two hundred sixty-one million, five hundred forty-one thousand, six hundred thirteen".