261567537197 has 4 divisors (see below), whose sum is σ = 261829892796. Its totient is φ = 261305181600.

The previous prime is 261567537181. The next prime is 261567537211. The reversal of 261567537197 is 791735765162.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 791735765162 = 2 ⋅395867882581.

It can be written as a sum of positive squares in 2 ways, for example, as 207358193956 + 54209343241 = 455366^2 + 232829^2 .

It is a cyclic number.

It is not a de Polignac number, because 261567537197 - 2⁴ = 261567537181 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 (261567537137) 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, 131176304 + ... + 131178297.

It is an arithmetic number, because the mean of its divisors is an integer number (65457473199).

Almost surely, 2^261567537197 is an apocalyptic number.

It is an amenable number.

261567537197 is a deficient number, since it is larger than the sum of its proper divisors (262355599).

261567537197 is an equidigital number, since it uses as much as digits as its factorization.

261567537197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262355598.

The product of its digits is 16669800, while the sum is 59.

The spelling of 261567537197 in words is "two hundred sixty-one billion, five hundred sixty-seven million, five hundred thirty-seven thousand, one hundred ninety-seven".