640173672 has 64 divisors (see below), whose sum is σ = 1821657600. Its totient is φ = 208183680.

The previous prime is 640173661. The next prime is 640173673. The reversal of 640173672 is 276371046.

640173672 is a `hidden beast` number, since 640 + 1 + 7 + 3 + 6 + 7 + 2 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (640173673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27288 + ... + 44999.

It is an arithmetic number, because the mean of its divisors is an integer number (28463400).

Almost surely, 2^640173672 is an apocalyptic number.

It is an amenable number.

640173672 is an abundant number, since it is smaller than the sum of its proper divisors (1181483928).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640173672 is a wasteful number, since it uses less digits than its factorization.

640173672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72343 (or 72333 counting only the distinct ones).

The product of its (nonzero) digits is 42336, while the sum is 36.

The square root of 640173672 is about 25301.6535428023. The cubic root of 640173672 is about 861.8518200006.

The spelling of 640173672 in words is "six hundred forty million, one hundred seventy-three thousand, six hundred seventy-two".