666719 has 4 divisors (see below), whose sum is σ = 673296. Its totient is φ = 660144.

The previous prime is 666707. The next prime is 666727. The reversal of 666719 is 917666.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666719 is a prime.

It is a super-2 number, since 2×666719² = 889028449922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3134 + ... + 3339.

It is an arithmetic number, because the mean of its divisors is an integer number (168324).

2⁶⁶⁶⁷¹⁹ is an apocalyptic number.

666719 is a deficient number, since it is larger than the sum of its proper divisors (6577).

666719 is a wasteful number, since it uses less digits than its factorization.

666719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6576.

The product of its digits is 13608, while the sum is 35.

The square root of 666719 is about 816.5286277896. The cubic root of 666719 is about 87.3603322827.

The spelling of 666719 in words is "six hundred sixty-six thousand, seven hundred nineteen".