640065531 has 8 divisors (see below), whose sum is σ = 975337984. Its totient is φ = 365751720.

The previous prime is 640065511. The next prime is 640065563. The reversal of 640065531 is 135560046.

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

It is not a de Polignac number, because 640065531 - 2⁵ = 640065499 is a prime.

It is a super-2 number, since 2×640065531² = 819367767948623922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640065511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15239635 + ... + 15239676.

It is an arithmetic number, because the mean of its divisors is an integer number (121917248).

Almost surely, 2^640065531 is an apocalyptic number.

640065531 is a deficient number, since it is larger than the sum of its proper divisors (335272453).

640065531 is a wasteful number, since it uses less digits than its factorization.

640065531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30479321.

The product of its (nonzero) digits is 10800, while the sum is 30.

The square root of 640065531 is about 25299.5164183033. The cubic root of 640065531 is about 861.8032879797.

The spelling of 640065531 in words is "six hundred forty million, sixty-five thousand, five hundred thirty-one".