640660206 has 16 divisors (see below), whose sum is σ = 1293761664. Its totient is φ = 211479864.

The previous prime is 640660177. The next prime is 640660213. The reversal of 640660206 is 602066046.

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, 517716 + ... + 518951.

It is an arithmetic number, because the mean of its divisors is an integer number (80860104).

Almost surely, 2^640660206 is an apocalyptic number.

640660206 is an abundant number, since it is smaller than the sum of its proper divisors (653101458).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640660206 is a wasteful number, since it uses less digits than its factorization.

640660206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1036775.

The product of its (nonzero) digits is 10368, while the sum is 30.

The square root of 640660206 is about 25311.2663847544. The cubic root of 640660206 is about 862.0701014079.

The spelling of 640660206 in words is "six hundred forty million, six hundred sixty thousand, two hundred six".