665606765 has 16 divisors (see below), whose sum is σ = 841526400. Its totient is φ = 504004032.

The previous prime is 665606759. The next prime is 665606771. The reversal of 665606765 is 567606566.

It is an interprime number because it is at equal distance from previous prime (665606759) and next prime (665606771).

It is not a de Polignac number, because 665606765 - 2¹⁴ = 665590381 is a prime.

It is a super-2 number, since 2×665606765² = 886064731227530450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 133304 + ... + 138206.

It is an arithmetic number, because the mean of its divisors is an integer number (52595400).

Almost surely, 2^665606765 is an apocalyptic number.

It is an amenable number.

665606765 is a deficient number, since it is larger than the sum of its proper divisors (175919635).

665606765 is a wasteful number, since it uses less digits than its factorization.

665606765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6356.

The product of its (nonzero) digits is 1360800, while the sum is 47.

The square root of 665606765 is about 25799.3559028128. The cubic root of 665606765 is about 873.1172644809.

The spelling of 665606765 in words is "six hundred sixty-five million, six hundred six thousand, seven hundred sixty-five".