671764991 has 2 divisors, whose sum is σ = 671764992. Its totient is φ = 671764990.

The previous prime is 671764949. The next prime is 671765011. The reversal of 671764991 is 199467176.

671764991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-671764991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (671764591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335882495 + 335882496.

It is an arithmetic number, because the mean of its divisors is an integer number (335882496).

Almost surely, 2^671764991 is an apocalyptic number.

671764991 is a deficient number, since it is larger than the sum of its proper divisors (1).

671764991 is an equidigital number, since it uses as much as digits as its factorization.

671764991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 571536, while the sum is 50.

The square root of 671764991 is about 25918.4295627648. The cubic root of 671764991 is about 875.8017102776.

The spelling of 671764991 in words is "six hundred seventy-one million, seven hundred sixty-four thousand, nine hundred ninety-one".