261778219592 has 36 divisors (see below), whose sum is σ = 504561688155. Its totient is φ = 127325517696.

The previous prime is 261778219529. The next prime is 261778219597. The reversal of 261778219592 is 295912877162.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 5 ways, for example, as 257704461316 + 4073758276 = 507646^2 + 63826^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=361786.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261778219597) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 53541884 + ... + 53546772.

Almost surely, 2^261778219592 is an apocalyptic number.

It is an amenable number.

261778219592 is a deficient number, since it is larger than the sum of its proper divisors (242783468563).

261778219592 is an frugal number, since it uses more digits than its factorization.

261778219592 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9858 (or 4928 counting only the distinct ones).

The product of its digits is 7620480, while the sum is 59.

The spelling of 261778219592 in words is "two hundred sixty-one billion, seven hundred seventy-eight million, two hundred nineteen thousand, five hundred ninety-two".