261564324233503 has 4 divisors (see below), whose sum is σ = 261646293626928. Its totient is φ = 261482354840080.

The previous prime is 261564324233467. The next prime is 261564324233507. The reversal of 261564324233503 is 305332423465162.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261564324233503 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 (261564324233507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40984691926 + ... + 40984698307.

It is an arithmetic number, because the mean of its divisors is an integer number (65411573406732).

Almost surely, 2^{261564324233503} is an apocalyptic number.

261564324233503 is a deficient number, since it is larger than the sum of its proper divisors (81969393425).

261564324233503 is an equidigital number, since it uses as much as digits as its factorization.

261564324233503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81969393424.

The product of its (nonzero) digits is 9331200, while the sum is 49.

Adding to 261564324233503 its reverse (305332423465162), we get a palindrome (566896747698665).

The spelling of 261564324233503 in words is "two hundred sixty-one trillion, five hundred sixty-four billion, three hundred twenty-four million, two hundred thirty-three thousand, five hundred three".