261668415718 has 4 divisors (see below), whose sum is σ = 392502623580. Its totient is φ = 130834207858.

The previous prime is 261668415689. The next prime is 261668415769. The reversal of 261668415718 is 817514866162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 817514866162 = 2 ⋅408757433081.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65417103928 + ... + 65417103931.

It is an arithmetic number, because the mean of its divisors is an integer number (98125655895).

Almost surely, 2^261668415718 is an apocalyptic number.

261668415718 is a deficient number, since it is larger than the sum of its proper divisors (130834207862).

261668415718 is a wasteful number, since it uses less digits than its factorization.

261668415718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130834207861.

The product of its digits is 3870720, while the sum is 55.

The spelling of 261668415718 in words is "two hundred sixty-one billion, six hundred sixty-eight million, four hundred fifteen thousand, seven hundred eighteen".