667727991 has 24 divisors (see below), whose sum is σ = 1107160704. Its totient is φ = 379869840.

The previous prime is 667727959. The next prime is 667727993. The reversal of 667727991 is 199727766.

It is a happy number.

It is not a de Polignac number, because 667727991 - 2⁵ = 667727959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667727993) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9045 + ... + 37646.

It is an arithmetic number, because the mean of its divisors is an integer number (46131696).

Almost surely, 2^667727991 is an apocalyptic number.

667727991 is a deficient number, since it is larger than the sum of its proper divisors (439432713).

667727991 is a wasteful number, since it uses less digits than its factorization.

667727991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46931 (or 46928 counting only the distinct ones).

The product of its digits is 2000376, while the sum is 54.

The square root of 667727991 is about 25840.4332587517. The cubic root of 667727991 is about 874.0437950535.

The spelling of 667727991 in words is "six hundred sixty-seven million, seven hundred twenty-seven thousand, nine hundred ninety-one".