643531 has 8 divisors (see below), whose sum is σ = 741600. Its totient is φ = 547008.

The previous prime is 643523. The next prime is 643547. The reversal of 643531 is 135346.

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

It is not a de Polignac number, because 643531 - 2³ = 643523 is a prime.

It is a super-2 number, since 2×643531² = 828264295922, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (643031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 735 + ... + 1351.

It is an arithmetic number, because the mean of its divisors is an integer number (92700).

2⁶⁴³⁵³¹ is an apocalyptic number.

643531 is a deficient number, since it is larger than the sum of its proper divisors (98069).

643531 is a wasteful number, since it uses less digits than its factorization.

643531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 773.

The product of its digits is 1080, while the sum is 22.

The square root of 643531 is about 802.2038394323. The cubic root of 643531 is about 86.3355826283.

Adding to 643531 its reverse (135346), we get a palindrome (778877).

The spelling of 643531 in words is "six hundred forty-three thousand, five hundred thirty-one".