640664019 has 8 divisors (see below), whose sum is σ = 949131920. Its totient is φ = 427109328.

The previous prime is 640663999. The next prime is 640664033. The reversal of 640664019 is 910466046.

640664019 is a `hidden beast` number, since 6 + 4 + 0 + 6 + 640 + 1 + 9 = 666.

It is not a de Polignac number, because 640664019 - 2²⁰ = 639615443 is a prime.

It is a super-3 number, since 3×640664019³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640664069) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11864122 + ... + 11864175.

It is an arithmetic number, because the mean of its divisors is an integer number (118641490).

Almost surely, 2^640664019 is an apocalyptic number.

640664019 is a deficient number, since it is larger than the sum of its proper divisors (308467901).

640664019 is a wasteful number, since it uses less digits than its factorization.

640664019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23728306 (or 23728300 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 640664019 is about 25311.3417068317. The cubic root of 640664019 is about 862.0718116576.

The spelling of 640664019 in words is "six hundred forty million, six hundred sixty-four thousand, nineteen".