261513323437 has 4 divisors (see below), whose sum is σ = 261667792540. Its totient is φ = 261358854336.

The previous prime is 261513323387. The next prime is 261513323453. The reversal of 261513323437 is 734323315162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 734323315162 = 2 ⋅367161657581.

It can be written as a sum of positive squares in 2 ways, for example, as 188239705956 + 73273617481 = 433866^2 + 270691^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261513323437 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261513323437.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261513323837) 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, 77232012 + ... + 77235397.

It is an arithmetic number, because the mean of its divisors is an integer number (65416948135).

Almost surely, 2^261513323437 is an apocalyptic number.

It is an amenable number.

261513323437 is a deficient number, since it is larger than the sum of its proper divisors (154469103).

261513323437 is a wasteful number, since it uses less digits than its factorization.

261513323437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154469102.

The product of its digits is 272160, while the sum is 40.

Adding to 261513323437 its reverse (734323315162), we get a palindrome (995836638599).

The spelling of 261513323437 in words is "two hundred sixty-one billion, five hundred thirteen million, three hundred twenty-three thousand, four hundred thirty-seven".