261553314672005 has 4 divisors (see below), whose sum is σ = 313863977606412. Its totient is φ = 209242651737600.

The previous prime is 261553314671989. The next prime is 261553314672019. The reversal of 261553314672005 is 500276413355162.

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

It can be written as a sum of positive squares in 2 ways, for example, as 158177759611876 + 103375555060129 = 12576874^2 + 10167377^2 .

It is not a de Polignac number, because 261553314672005 - 2⁴ = 261553314671989 is a prime.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 26155331467196 + ... + 26155331467205.

It is an arithmetic number, because the mean of its divisors is an integer number (78465994401603).

Almost surely, 2^{261553314672005} is an apocalyptic number.

It is an amenable number.

261553314672005 is a deficient number, since it is larger than the sum of its proper divisors (52310662934407).

261553314672005 is an equidigital number, since it uses as much as digits as its factorization.

261553314672005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52310662934406.

The product of its (nonzero) digits is 4536000, while the sum is 50.

The spelling of 261553314672005 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, three hundred fourteen million, six hundred seventy-two thousand, five".