667720609 has 8 divisors (see below), whose sum is σ = 672392448. Its totient is φ = 663057120.

The previous prime is 667720597. The next prime is 667720633. The reversal of 667720609 is 906027766.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 667720609 - 2¹⁵ = 667687841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (667720909) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 311389 + ... + 313525.

It is an arithmetic number, because the mean of its divisors is an integer number (84049056).

Almost surely, 2^667720609 is an apocalyptic number.

It is an amenable number.

667720609 is a deficient number, since it is larger than the sum of its proper divisors (4671839).

667720609 is a wasteful number, since it uses less digits than its factorization.

667720609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4175.

The product of its (nonzero) digits is 190512, while the sum is 43.

The square root of 667720609 is about 25840.2904201946. The cubic root of 667720609 is about 874.0405740737.

The spelling of 667720609 in words is "six hundred sixty-seven million, seven hundred twenty thousand, six hundred nine".