261657136766777 has 4 divisors (see below), whose sum is σ = 275428565017680. Its totient is φ = 247885708515876.

The previous prime is 261657136766747. The next prime is 261657136766827. The reversal of 261657136766777 is 777667631756162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261657136766777 - 2³⁶ = 261588417290041 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261657136766698 and 261657136766707.

It is not an unprimeable number, because it can be changed into a prime (261657136766717) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6885714125423 + ... + 6885714125460.

It is an arithmetic number, because the mean of its divisors is an integer number (68857141254420).

Almost surely, 2^{261657136766777} is an apocalyptic number.

It is an amenable number.

261657136766777 is a deficient number, since it is larger than the sum of its proper divisors (13771428250903).

261657136766777 is a wasteful number, since it uses less digits than its factorization.

261657136766777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13771428250902.

The product of its digits is 3920736960, while the sum is 77.

The spelling of 261657136766777 in words is "two hundred sixty-one trillion, six hundred fifty-seven billion, one hundred thirty-six million, seven hundred sixty-six thousand, seven hundred seventy-seven".