640036779 has 8 divisors (see below), whose sum is σ = 867846720. Its totient is φ = 419459016.

The previous prime is 640036777. The next prime is 640036781. The reversal of 640036779 is 977630046.

It is an interprime number because it is at equal distance from previous prime (640036777) and next prime (640036781).

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

It is not a de Polignac number, because 640036779 - 2¹ = 640036777 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 640036779.

It is not an unprimeable number, because it can be changed into a prime (640036777) 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, 1807837 + ... + 1808190.

It is an arithmetic number, because the mean of its divisors is an integer number (108480840).

Almost surely, 2^640036779 is an apocalyptic number.

640036779 is a deficient number, since it is larger than the sum of its proper divisors (227809941).

640036779 is a wasteful number, since it uses less digits than its factorization.

640036779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3616089.

The product of its (nonzero) digits is 190512, while the sum is 42.

The square root of 640036779 is about 25298.9481797169. The cubic root of 640036779 is about 861.7903836035.

The spelling of 640036779 in words is "six hundred forty million, thirty-six thousand, seven hundred seventy-nine".