666816519 has 4 divisors (see below), whose sum is σ = 889088696. Its totient is φ = 444544344.

The previous prime is 666816511. The next prime is 666816581. The reversal of 666816519 is 915618666.

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

It is not a de Polignac number, because 666816519 - 2³ = 666816511 is a prime.

It is a super-2 number, since 2×666816519² = 889288540022554722, 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 (666816511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111136084 + ... + 111136089.

It is an arithmetic number, because the mean of its divisors is an integer number (222272174).

Almost surely, 2^666816519 is an apocalyptic number.

666816519 is a deficient number, since it is larger than the sum of its proper divisors (222272177).

666816519 is a wasteful number, since it uses less digits than its factorization.

666816519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222272176.

The product of its digits is 466560, while the sum is 48.

The square root of 666816519 is about 25822.7906896214. The cubic root of 666816519 is about 873.6459138682.

The spelling of 666816519 in words is "six hundred sixty-six million, eight hundred sixteen thousand, five hundred nineteen".