640009373 has 4 divisors (see below), whose sum is σ = 642388860. Its totient is φ = 637629888.

The previous prime is 640009351. The next prime is 640009379. The reversal of 640009373 is 373900046.

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

It can be written as a sum of positive squares in 2 ways, for example, as 125037124 + 514972249 = 11182^2 + 22693^2 .

It is a cyclic number.

It is not a de Polignac number, because 640009373 - 2²⁰ = 638960797 is a prime.

It is a super-2 number, since 2×640009373² = 819223995055706258, 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 (640009379) 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, 1189340 + ... + 1189877.

It is an arithmetic number, because the mean of its divisors is an integer number (160597215).

Almost surely, 2^640009373 is an apocalyptic number.

It is an amenable number.

640009373 is a deficient number, since it is larger than the sum of its proper divisors (2379487).

640009373 is a wasteful number, since it uses less digits than its factorization.

640009373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2379486.

The product of its (nonzero) digits is 13608, while the sum is 32.

The square root of 640009373 is about 25298.4065308470. The cubic root of 640009373 is about 861.7780829748.

The spelling of 640009373 in words is "six hundred forty million, nine thousand, three hundred seventy-three".