640978854 has 8 divisors (see below), whose sum is σ = 1281957720. Its totient is φ = 213659616.

The previous prime is 640978837. The next prime is 640978859. The reversal of 640978854 is 458879046.

640978854 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

640978854 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 640978797 and 640978806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640978859) 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, 53414899 + ... + 53414910.

It is an arithmetic number, because the mean of its divisors is an integer number (160244715).

Almost surely, 2^640978854 is an apocalyptic number.

640978854 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

640978854 is a wasteful number, since it uses less digits than its factorization.

640978854 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106829814.

The product of its (nonzero) digits is 1935360, while the sum is 51.

The square root of 640978854 is about 25317.5601905081. The cubic root of 640978854 is about 862.2130015918.

The spelling of 640978854 in words is "six hundred forty million, nine hundred seventy-eight thousand, eight hundred fifty-four".