640016655 has 8 divisors (see below), whose sum is σ = 1024026672. Its totient is φ = 341342208.

The previous prime is 640016651. The next prime is 640016659. The reversal of 640016655 is 556610046.

It is an interprime number because it is at equal distance from previous prime (640016651) and next prime (640016659).

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

It is not a de Polignac number, because 640016655 - 2² = 640016651 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640016651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21333874 + ... + 21333903.

It is an arithmetic number, because the mean of its divisors is an integer number (128003334).

Almost surely, 2^640016655 is an apocalyptic number.

640016655 is a deficient number, since it is larger than the sum of its proper divisors (384010017).

640016655 is a wasteful number, since it uses less digits than its factorization.

640016655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42667785.

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 640016655 is about 25298.5504525457. The cubic root of 640016655 is about 861.7813513874.

The spelling of 640016655 in words is "six hundred forty million, sixteen thousand, six hundred fifty-five".