640017631 has 16 divisors (see below), whose sum is σ = 710784000. Its totient is φ = 571428000.

The previous prime is 640017613. The next prime is 640017671. The reversal of 640017631 is 136710046.

It is not a de Polignac number, because 640017631 - 2¹¹ = 640015583 is a prime.

It is a super-2 number, since 2×640017631² = 819245135981704322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640017631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640017671) 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, 171081 + ... + 174781.

It is an arithmetic number, because the mean of its divisors is an integer number (44424000).

Almost surely, 2^640017631 is an apocalyptic number.

640017631 is a deficient number, since it is larger than the sum of its proper divisors (70766369).

640017631 is a wasteful number, since it uses less digits than its factorization.

640017631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3990.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 640017631 is about 25298.5697421811. The cubic root of 640017631 is about 861.7817894480.

Adding to 640017631 its reverse (136710046), we get a palindrome (776727677).

The spelling of 640017631 in words is "six hundred forty million, seventeen thousand, six hundred thirty-one".