261251165345 has 4 divisors (see below), whose sum is σ = 313501398420. Its totient is φ = 209000932272.

The previous prime is 261251165341. The next prime is 261251165347. The reversal of 261251165345 is 543561152162.

261251165345 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 94342965409 + 166908199936 = 307153^2 + 408544^2 .

It is a cyclic number.

It is not a de Polignac number, because 261251165345 - 2² = 261251165341 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261251165341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26125116530 + ... + 26125116539.

It is an arithmetic number, because the mean of its divisors is an integer number (78375349605).

Almost surely, 2^261251165345 is an apocalyptic number.

It is an amenable number.

261251165345 is a deficient number, since it is larger than the sum of its proper divisors (52250233075).

261251165345 is an equidigital number, since it uses as much as digits as its factorization.

261251165345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52250233074.

The product of its digits is 216000, while the sum is 41.

The spelling of 261251165345 in words is "two hundred sixty-one billion, two hundred fifty-one million, one hundred sixty-five thousand, three hundred forty-five".