666640719 has 16 divisors (see below), whose sum is σ = 1021672800. Its totient is φ = 429101568.

The previous prime is 666640697. The next prime is 666640753. The reversal of 666640719 is 917046666.

It is a happy number.

It is not a de Polignac number, because 666640719 - 2¹¹ = 666638671 is a prime.

It is a super-2 number, since 2×666640719² = 888819696457673922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666640769) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 424914 + ... + 426479.

It is an arithmetic number, because the mean of its divisors is an integer number (63854550).

Almost surely, 2^666640719 is an apocalyptic number.

666640719 is a deficient number, since it is larger than the sum of its proper divisors (355032081).

666640719 is a wasteful number, since it uses less digits than its factorization.

666640719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851431 (or 851425 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 45.

The square root of 666640719 is about 25819.3864954224. The cubic root of 666640719 is about 873.5691309019.

The spelling of 666640719 in words is "six hundred sixty-six million, six hundred forty thousand, seven hundred nineteen".