640431543 has 8 divisors (see below), whose sum is σ = 854128000. Its totient is φ = 426844728.

The previous prime is 640431523. The next prime is 640431593. The reversal of 640431543 is 345134046.

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

It is not a de Polignac number, because 640431543 - 2¹⁶ = 640366007 is a prime.

It is a super-2 number, since 2×640431543² = 820305122538721698, 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 640431543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640431503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12643 + ... + 37956.

It is an arithmetic number, because the mean of its divisors is an integer number (106766000).

Almost surely, 2^640431543 is an apocalyptic number.

640431543 is a deficient number, since it is larger than the sum of its proper divisors (213696457).

640431543 is a wasteful number, since it uses less digits than its factorization.

640431543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54821.

The product of its (nonzero) digits is 17280, while the sum is 30.

The square root of 640431543 is about 25306.7489614925. The cubic root of 640431543 is about 861.9675264960.

Adding to 640431543 its reverse (345134046), we get a palindrome (985565589).

The spelling of 640431543 in words is "six hundred forty million, four hundred thirty-one thousand, five hundred forty-three".