640842887 has 4 divisors (see below), whose sum is σ = 674571480. Its totient is φ = 607114296.

The previous prime is 640842871. The next prime is 640842913. The reversal of 640842887 is 788248046.

It is a happy number.

640842887 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 640842887 - 2⁴ = 640842871 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640842817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16864268 + ... + 16864305.

It is an arithmetic number, because the mean of its divisors is an integer number (168642870).

Almost surely, 2^640842887 is an apocalyptic number.

640842887 is a deficient number, since it is larger than the sum of its proper divisors (33728593).

640842887 is a wasteful number, since it uses less digits than its factorization.

640842887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33728592.

The product of its (nonzero) digits is 688128, while the sum is 47.

The square root of 640842887 is about 25314.8748169925. The cubic root of 640842887 is about 862.1520319229.

The spelling of 640842887 in words is "six hundred forty million, eight hundred forty-two thousand, eight hundred eighty-seven".