640854173 has 4 divisors (see below), whose sum is σ = 674583360. Its totient is φ = 607124988.

The previous prime is 640854169. The next prime is 640854187. The reversal of 640854173 is 371458046.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 371458046 = 2 ⋅185729023.

It is a cyclic number.

It is not a de Polignac number, because 640854173 - 2² = 640854169 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640854163) 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, 16864565 + ... + 16864602.

It is an arithmetic number, because the mean of its divisors is an integer number (168645840).

Almost surely, 2^640854173 is an apocalyptic number.

It is an amenable number.

640854173 is a deficient number, since it is larger than the sum of its proper divisors (33729187).

640854173 is a wasteful number, since it uses less digits than its factorization.

640854173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33729186.

The product of its (nonzero) digits is 80640, while the sum is 38.

The square root of 640854173 is about 25315.0977284308. The cubic root of 640854173 is about 862.1570930650.

The spelling of 640854173 in words is "six hundred forty million, eight hundred fifty-four thousand, one hundred seventy-three".