640168639 has 8 divisors (see below), whose sum is σ = 701913168. Its totient is φ = 579015360.

The previous prime is 640168601. The next prime is 640168657. The reversal of 640168639 is 936861046.

640168639 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.

It is not a de Polignac number, because 640168639 - 2¹⁹ = 639644351 is a prime.

It is a super-2 number, since 2×640168639² = 819631772718224642, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640168595 and 640168604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640160639) 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, 145542 + ... + 149875.

It is an arithmetic number, because the mean of its divisors is an integer number (87739146).

Almost surely, 2^640168639 is an apocalyptic number.

640168639 is a deficient number, since it is larger than the sum of its proper divisors (61744529).

640168639 is a wasteful number, since it uses less digits than its factorization.

640168639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295625.

The product of its (nonzero) digits is 186624, while the sum is 43.

The square root of 640168639 is about 25301.5540827041. The cubic root of 640168639 is about 861.8495613888.

The spelling of 640168639 in words is "six hundred forty million, one hundred sixty-eight thousand, six hundred thirty-nine".