667646009 has 4 divisors (see below), whose sum is σ = 683930100. Its totient is φ = 651361920.

The previous prime is 667646003. The next prime is 667646011. The reversal of 667646009 is 900646766.

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 156750400 + 510895609 = 12520^2 + 22603^2 .

It is a cyclic number.

It is not a de Polignac number, because 667646009 - 2⁸ = 667645753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (667646003) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 8141984 + ... + 8142065.

It is an arithmetic number, because the mean of its divisors is an integer number (170982525).

Almost surely, 2^667646009 is an apocalyptic number.

It is an amenable number.

667646009 is a deficient number, since it is larger than the sum of its proper divisors (16284091).

667646009 is a wasteful number, since it uses less digits than its factorization.

667646009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16284090.

The product of its (nonzero) digits is 326592, while the sum is 44.

The square root of 667646009 is about 25838.8468976462. The cubic root of 667646009 is about 874.0080226072.

The spelling of 667646009 in words is "six hundred sixty-seven million, six hundred forty-six thousand, nine".