666751 has 2 divisors, whose sum is σ = 666752. Its totient is φ = 666750.

The previous prime is 666749. The next prime is 666769. The reversal of 666751 is 157666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666751 - 2¹ = 666749 is a prime.

Together with 666749, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (676751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333375 + 333376.

It is an arithmetic number, because the mean of its divisors is an integer number (333376).

2⁶⁶⁶⁷⁵¹ is an apocalyptic number.

666751 is a deficient number, since it is larger than the sum of its proper divisors (1).

666751 is an equidigital number, since it uses as much as digits as its factorization.

666751 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 31.

The square root of 666751 is about 816.5482227034. The cubic root of 666751 is about 87.3617299159.

The spelling of 666751 in words is "six hundred sixty-six thousand, seven hundred fifty-one".