640143521 has 8 divisors (see below), whose sum is σ = 689524224. Its totient is φ = 592558560.

The previous prime is 640143509. The next prime is 640143529. The reversal of 640143521 is 125341046.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640143521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640143529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 448196 + ... + 449621.

It is an arithmetic number, because the mean of its divisors is an integer number (86190528).

Almost surely, 2^640143521 is an apocalyptic number.

It is an amenable number.

640143521 is a deficient number, since it is larger than the sum of its proper divisors (49380703).

640143521 is a wasteful number, since it uses less digits than its factorization.

640143521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897871.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 640143521 is about 25301.0577051632. The cubic root of 640143521 is about 861.8382892441.

Adding to 640143521 its reverse (125341046), we get a palindrome (765484567).

The spelling of 640143521 in words is "six hundred forty million, one hundred forty-three thousand, five hundred twenty-one".