918131793077561 has 4 divisors (see below), whose sum is σ = 918139705326324. Its totient is φ = 918123880828800.

The previous prime is 918131793077557. The next prime is 918131793077567. The reversal of 918131793077561 is 165770397131819.

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 730894469203600 + 187237323873961 = 27035060^2 + 13683469^2 .

It is a cyclic number.

It is not a de Polignac number, because 918131793077561 - 2² = 918131793077557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 918131793077491 and 918131793077500.

It is not an unprimeable number, because it can be changed into a prime (918131793077567) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3955950320 + ... + 3956182401.

It is an arithmetic number, because the mean of its divisors is an integer number (229534926331581).

Almost surely, 2^{918131793077561} is an apocalyptic number.

It is an amenable number.

918131793077561 is a deficient number, since it is larger than the sum of its proper divisors (7912248763).

918131793077561 is a wasteful number, since it uses less digits than its factorization.

918131793077561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7912248762.

The product of its (nonzero) digits is 60011280, while the sum is 68.

The spelling of 918131793077561 in words is "nine hundred eighteen trillion, one hundred thirty-one billion, seven hundred ninety-three million, seventy-seven thousand, five hundred sixty-one".