640641276 has 108 divisors (see below), whose sum is σ = 1809931032. Its totient is φ = 190872000.

The previous prime is 640641247. The next prime is 640641299. The reversal of 640641276 is 672146046.

640641276 is a `hidden beast` number, since 6 + 4 + 0 + 641 + 2 + 7 + 6 = 666.

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

It is a self number, because there is not a number n which added to its sum of digits gives 640641276.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 264511 + ... + 266921.

Almost surely, 2^640641276 is an apocalyptic number.

640641276 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640641276, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (904965516).

640641276 is an abundant number, since it is smaller than the sum of its proper divisors (1169289756).

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

640641276 is a wasteful number, since it uses less digits than its factorization.

640641276 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2504 (or 2488 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The square root of 640641276 is about 25310.8924378419. The cubic root of 640641276 is about 862.0616106106.

The spelling of 640641276 in words is "six hundred forty million, six hundred forty-one thousand, two hundred seventy-six".