667991808 has 108 divisors (see below), whose sum is σ = 2101154328. Its totient is φ = 202414080.

The previous prime is 667991801. The next prime is 667991843. The reversal of 667991808 is 808199766.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667991801) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12166 + ... + 38522.

Almost surely, 2^667991808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 667991808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1050577164).

667991808 is an abundant number, since it is smaller than the sum of its proper divisors (1433162520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

667991808 is a wasteful number, since it uses less digits than its factorization.

667991808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26390 (or 26373 counting only the distinct ones).

The product of its (nonzero) digits is 1306368, while the sum is 54.

The square root of 667991808 is about 25845.5374871563. The cubic root of 667991808 is about 874.1588904484.

The spelling of 667991808 in words is "six hundred sixty-seven million, nine hundred ninety-one thousand, eight hundred eight".