667646765 has 4 divisors (see below), whose sum is σ = 801176124. Its totient is φ = 534117408.

The previous prime is 667646741. The next prime is 667646789. The reversal of 667646765 is 567646766.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (667646741) and next prime (667646789).

It can be written as a sum of positive squares in 2 ways, for example, as 235131556 + 432515209 = 15334^2 + 20797^2 .

It is a cyclic number.

It is not a de Polignac number, because 667646765 - 2¹⁸ = 667384621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66764672 + ... + 66764681.

It is an arithmetic number, because the mean of its divisors is an integer number (200294031).

Almost surely, 2^667646765 is an apocalyptic number.

It is an amenable number.

667646765 is a deficient number, since it is larger than the sum of its proper divisors (133529359).

667646765 is a wasteful number, since it uses less digits than its factorization.

667646765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133529358.

The product of its digits is 7620480, while the sum is 53.

The square root of 667646765 is about 25838.8615267778. The cubic root of 667646765 is about 874.0083524975.

Subtracting from 667646765 its reverse (567646766), we obtain a palindrome (99999999).

The spelling of 667646765 in words is "six hundred sixty-seven million, six hundred forty-six thousand, seven hundred sixty-five".