640606543641 has 45 divisors (see below), whose sum is σ = 966727398351. Its totient is φ = 422753784768.

The previous prime is 640606543631. The next prime is 640606543649. The reversal of 640606543641 is 146345606046.

The square root of 640606543641 is 800379.

It is a perfect power (a square), and thus also a powerful number.

640606543641 is a `hidden beast` number, since 6 + 4 + 0 + 60 + 6 + 543 + 6 + 41 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11288000025 + 629318543616 = 106245^2 + 793296^2 .

It is not a de Polignac number, because 640606543641 - 2¹⁷ = 640606412569 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640606543649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 813985050 + ... + 813985836.

Almost surely, 2^640606543641 is an apocalyptic number.

640606543641 is the 800379-th square number.

640606543641 is the 400190-th centered octagonal number.

It is an amenable number.

640606543641 is a deficient number, since it is larger than the sum of its proper divisors (326120854710).

640606543641 is an frugal number, since it uses more digits than its factorization.

640606543641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1812 (or 903 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 45.

The spelling of 640606543641 in words is "six hundred forty billion, six hundred six million, five hundred forty-three thousand, six hundred forty-one".