665767805 has 4 divisors (see below), whose sum is σ = 798921372. Its totient is φ = 532614240.

The previous prime is 665767789. The next prime is 665767813. The reversal of 665767805 is 508767566.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 508767566 = 2 ⋅254383783.

It can be written as a sum of positive squares in 2 ways, for example, as 132204004 + 533563801 = 11498^2 + 23099^2 .

It is not a de Polignac number, because 665767805 - 2⁴ = 665767789 is a prime.

It is a Duffinian number.

It is a congruent 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, 66576776 + ... + 66576785.

It is an arithmetic number, because the mean of its divisors is an integer number (199730343).

Almost surely, 2^665767805 is an apocalyptic number.

It is an amenable number.

665767805 is a deficient number, since it is larger than the sum of its proper divisors (133153567).

665767805 is a wasteful number, since it uses less digits than its factorization.

665767805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133153566.

The product of its (nonzero) digits is 2116800, while the sum is 50.

The square root of 665767805 is about 25802.4767222063. The cubic root of 665767805 is about 873.1876741549.

The spelling of 665767805 in words is "six hundred sixty-five million, seven hundred sixty-seven thousand, eight hundred five".