667275721 has 16 divisors (see below), whose sum is σ = 812318976. Its totient is φ = 535067136.

The previous prime is 667275683. The next prime is 667275727. The reversal of 667275721 is 127572766.

It is a cyclic number.

It is not a de Polignac number, because 667275721 - 2⁹ = 667275209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (667275727) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3085 + ... + 36661.

It is an arithmetic number, because the mean of its divisors is an integer number (50769936).

Almost surely, 2^667275721 is an apocalyptic number.

It is an amenable number.

667275721 is a deficient number, since it is larger than the sum of its proper divisors (145043255).

667275721 is a wasteful number, since it uses less digits than its factorization.

667275721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33768.

The product of its digits is 246960, while the sum is 43.

The square root of 667275721 is about 25831.6805686351. The cubic root of 667275721 is about 873.8464127481.

The spelling of 667275721 in words is "six hundred sixty-seven million, two hundred seventy-five thousand, seven hundred twenty-one".