640709885 has 8 divisors (see below), whose sum is σ = 769015296. Its totient is φ = 512458960.

The previous prime is 640709869. The next prime is 640709897. The reversal of 640709885 is 588907046.

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

It is not a de Polignac number, because 640709885 - 2⁴ = 640709869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19640 + ... + 40830.

It is an arithmetic number, because the mean of its divisors is an integer number (96126912).

Almost surely, 2^640709885 is an apocalyptic number.

It is an amenable number.

640709885 is a deficient number, since it is larger than the sum of its proper divisors (128305411).

640709885 is a wasteful number, since it uses less digits than its factorization.

640709885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27243.

The product of its (nonzero) digits is 483840, while the sum is 47.

The square root of 640709885 is about 25312.2477271379. The cubic root of 640709885 is about 862.0923834607.

The spelling of 640709885 in words is "six hundred forty million, seven hundred nine thousand, eight hundred eighty-five".