261555266045 has 64 divisors (see below), whose sum is σ = 348535249920. Its totient is φ = 187534921728.

The previous prime is 261555266039. The next prime is 261555266069. The reversal of 261555266045 is 540662555162.

It is not a de Polignac number, because 261555266045 - 2⁴ = 261555266029 is a prime.

It is a super-4 number, since 4×261555266045⁴ (a number of 47 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 66772427 + ... + 66776343.

It is an arithmetic number, because the mean of its divisors is an integer number (5445863280).

Almost surely, 2^261555266045 is an apocalyptic number.

It is an amenable number.

261555266045 is a deficient number, since it is larger than the sum of its proper divisors (86979983875).

261555266045 is a wasteful number, since it uses less digits than its factorization.

261555266045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4334.

The product of its (nonzero) digits is 2160000, while the sum is 47.

The spelling of 261555266045 in words is "two hundred sixty-one billion, five hundred fifty-five million, two hundred sixty-six thousand, forty-five".