261511211513 has 4 divisors (see below), whose sum is σ = 261608466420. Its totient is φ = 261413956608.

The previous prime is 261511211447. The next prime is 261511211519. The reversal of 261511211513 is 315112115162.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 37774643449 + 223736568064 = 194357^2 + 473008^2 .

It is a cyclic number.

It is not a de Polignac number, because 261511211513 - 2¹⁸ = 261510949369 is a prime.

It is a super-2 number, since 2×261511211513² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261511211519) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48623420 + ... + 48628797.

It is an arithmetic number, because the mean of its divisors is an integer number (65402116605).

Almost surely, 2^261511211513 is an apocalyptic number.

It is an amenable number.

261511211513 is a deficient number, since it is larger than the sum of its proper divisors (97254907).

261511211513 is an equidigital number, since it uses as much as digits as its factorization.

261511211513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97254906.

The product of its digits is 1800, while the sum is 29.

Adding to 261511211513 its reverse (315112115162), we get a palindrome (576623326675).

The spelling of 261511211513 in words is "two hundred sixty-one billion, five hundred eleven million, two hundred eleven thousand, five hundred thirteen".