640786984 has 24 divisors (see below), whose sum is σ = 1276312590. Its totient is φ = 301545728.

The previous prime is 640786973. The next prime is 640786997. The reversal of 640786984 is 489687046.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 631114884 + 9672100 = 25122^2 + 3110^2 .

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 136267 + ... + 140890.

Almost surely, 2^640786984 is an apocalyptic number.

It is an amenable number.

640786984 is a deficient number, since it is larger than the sum of its proper divisors (635525606).

640786984 is a wasteful number, since it uses less digits than its factorization.

640786984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277197 (or 277176 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 52.

The square root of 640786984 is about 25313.7706397131. The cubic root of 640786984 is about 862.1269616665.

The spelling of 640786984 in words is "six hundred forty million, seven hundred eighty-six thousand, nine hundred eighty-four".