667491661 has 8 divisors (see below), whose sum is σ = 677424384. Its totient is φ = 657573840.

The previous prime is 667491647. The next prime is 667491673. The reversal of 667491661 is 166194766.

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 667491661 - 2¹⁵ = 667458893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667491611) 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, 113356 + ... + 119098.

It is an arithmetic number, because the mean of its divisors is an integer number (84678048).

Almost surely, 2^667491661 is an apocalyptic number.

It is an amenable number.

667491661 is a deficient number, since it is larger than the sum of its proper divisors (9932723).

667491661 is a wasteful number, since it uses less digits than its factorization.

667491661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7451.

The product of its digits is 326592, while the sum is 46.

The square root of 667491661 is about 25835.8599818160. The cubic root of 667491661 is about 873.9406656618.

The spelling of 667491661 in words is "six hundred sixty-seven million, four hundred ninety-one thousand, six hundred sixty-one".