2661256505 has 8 divisors (see below), whose sum is σ = 3198896712. Its totient is φ = 2125412608.

The previous prime is 2661256457. The next prime is 2661256553. The reversal of 2661256505 is 5056521662.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (2661256457) and next prime (2661256553).

It can be written as a sum of positive squares in 4 ways, for example, as 20529961 + 2640726544 = 4531^2 + 51388^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2661256505 - 2²⁶ = 2594147641 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 445814 + ... + 451743.

It is an arithmetic number, because the mean of its divisors is an integer number (399862089).

Almost surely, 2^2661256505 is an apocalyptic number.

It is an amenable number.

2661256505 is a deficient number, since it is larger than the sum of its proper divisors (537640207).

2661256505 is an equidigital number, since it uses as much as digits as its factorization.

2661256505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 898155.

The product of its (nonzero) digits is 108000, while the sum is 38.

The square root of 2661256505 is about 51587.3676882238. The cubic root of 2661256505 is about 1385.7841146329.

The spelling of 2661256505 in words is "two billion, six hundred sixty-one million, two hundred fifty-six thousand, five hundred five".