640518187 has 8 divisors (see below), whose sum is σ = 661928960. Its totient is φ = 619154280.

The previous prime is 640518181. The next prime is 640518199. The reversal of 640518187 is 781815046.

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

It is a cyclic number.

It is not a de Polignac number, because 640518187 - 2⁷ = 640518059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640518181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17248 + ... + 39730.

It is an arithmetic number, because the mean of its divisors is an integer number (82741120).

Almost surely, 2^640518187 is an apocalyptic number.

640518187 is a deficient number, since it is larger than the sum of its proper divisors (21410773).

640518187 is a wasteful number, since it uses less digits than its factorization.

640518187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23433.

The product of its (nonzero) digits is 53760, while the sum is 40.

The square root of 640518187 is about 25308.4607789569. The cubic root of 640518187 is about 862.0063966128.

The spelling of 640518187 in words is "six hundred forty million, five hundred eighteen thousand, one hundred eighty-seven".