261033155505 has 24 divisors (see below), whose sum is σ = 452519444520. Its totient is φ = 139198613760.

The previous prime is 261033155503. The next prime is 261033155557. The reversal of 261033155505 is 505551330162.

261033155505 is a `hidden beast` number, since 2 + 61 + 0 + 33 + 15 + 550 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 42225318144 + 218807837361 = 205488^2 + 467769^2 .

It is not a de Polignac number, because 261033155505 - 2¹ = 261033155503 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261033155505.

It is not an unprimeable number, because it can be changed into a prime (261033155503) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 61986 + ... + 725195.

It is an arithmetic number, because the mean of its divisors is an integer number (18854976855).

Almost surely, 2^261033155505 is an apocalyptic number.

It is an amenable number.

261033155505 is a deficient number, since it is larger than the sum of its proper divisors (191486289015).

261033155505 is a wasteful number, since it uses less digits than its factorization.

261033155505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 794561 (or 794558 counting only the distinct ones).

The product of its (nonzero) digits is 67500, while the sum is 36.

Adding to 261033155505 its reverse (505551330162), we get a palindrome (766584485667).

The spelling of 261033155505 in words is "two hundred sixty-one billion, thirty-three million, one hundred fifty-five thousand, five hundred five".