640539493 has 16 divisors (see below), whose sum is σ = 710197632. Its totient is φ = 572824000.

The previous prime is 640539491. The next prime is 640539499. The reversal of 640539493 is 394935046.

It is a cyclic number.

It is not a de Polignac number, because 640539493 - 2¹ = 640539491 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640539491) 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 15 ways as a sum of consecutive naturals, for example, 603183 + ... + 604243.

It is an arithmetic number, because the mean of its divisors is an integer number (44387352).

Almost surely, 2^640539493 is an apocalyptic number.

It is an amenable number.

640539493 is a deficient number, since it is larger than the sum of its proper divisors (69658139).

640539493 is a wasteful number, since it uses less digits than its factorization.

640539493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1916.

The product of its (nonzero) digits is 349920, while the sum is 43.

The square root of 640539493 is about 25308.8817018848. The cubic root of 640539493 is about 862.0159543453.

The spelling of 640539493 in words is "six hundred forty million, five hundred thirty-nine thousand, four hundred ninety-three".