640409729985 has 48 divisors (see below), whose sum is σ = 1118110526208. Its totient is φ = 339078700800.

The previous prime is 640409729963. The next prime is 640409729989. The reversal of 640409729985 is 589927904046.

640409729985 is a `hidden beast` number, since 64 + 0 + 409 + 7 + 2 + 99 + 85 = 666.

It is not a de Polignac number, because 640409729985 - 2¹² = 640409725889 is a prime.

It is a hoax number, since the sum of its digits (63) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (640409729989) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3333354 + ... + 3520236.

It is an arithmetic number, because the mean of its divisors is an integer number (23293969296).

Almost surely, 2^640409729985 is an apocalyptic number.

It is an amenable number.

640409729985 is a deficient number, since it is larger than the sum of its proper divisors (477700796223).

640409729985 is a wasteful number, since it uses less digits than its factorization.

640409729985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187446 (or 187443 counting only the distinct ones).

The product of its (nonzero) digits is 39191040, while the sum is 63.

The spelling of 640409729985 in words is "six hundred forty billion, four hundred nine million, seven hundred twenty-nine thousand, nine hundred eighty-five".