640341655 has 16 divisors (see below), whose sum is σ = 776109600. Its totient is φ = 507164032.

The previous prime is 640341631. The next prime is 640341659. The reversal of 640341655 is 556143046.

It is a cyclic number.

It is not a de Polignac number, because 640341655 - 2¹¹ = 640339607 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640341655.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640341659) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 257277 + ... + 259753.

It is an arithmetic number, because the mean of its divisors is an integer number (48506850).

Almost surely, 2^640341655 is an apocalyptic number.

640341655 is a deficient number, since it is larger than the sum of its proper divisors (135767945).

640341655 is a wasteful number, since it uses less digits than its factorization.

640341655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2978.

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 640341655 is about 25304.9729302365. The cubic root of 640341655 is about 861.9271973548.

The spelling of 640341655 in words is "six hundred forty million, three hundred forty-one thousand, six hundred fifty-five".