261543030755665 has 4 divisors (see below), whose sum is σ = 313851636906804. Its totient is φ = 209234424604528.

The previous prime is 261543030755641. The next prime is 261543030755689. The reversal of 261543030755665 is 566557030345162.

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

It is an interprime number because it is at equal distance from previous prime (261543030755641) and next prime (261543030755689).

It can be written as a sum of positive squares in 2 ways, for example, as 206725532470209 + 54817498285456 = 14377953^2 + 7403884^2 .

It is a cyclic number.

It is not a de Polignac number, because 261543030755665 - 2³¹ = 261540883272017 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26154303075562 + ... + 26154303075571.

It is an arithmetic number, because the mean of its divisors is an integer number (78462909226701).

Almost surely, 2^{261543030755665} is an apocalyptic number.

It is an amenable number.

261543030755665 is a deficient number, since it is larger than the sum of its proper divisors (52308606151139).

261543030755665 is an equidigital number, since it uses as much as digits as its factorization.

261543030755665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52308606151138.

The product of its (nonzero) digits is 68040000, while the sum is 58.

The spelling of 261543030755665 in words is "two hundred sixty-one trillion, five hundred forty-three billion, thirty million, seven hundred fifty-five thousand, six hundred sixty-five".