643281 has 8 divisors (see below), whose sum is σ = 885504. Its totient is φ = 414960.

The previous prime is 643273. The next prime is 643301. The reversal of 643281 is 182346.

It is a happy number.

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

It is not a de Polignac number, because 643281 - 2³ = 643273 is a prime.

It is a super-2 number, since 2×643281² = 827620889922, which contains 22 as substring.

643281 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643231) 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, 3366 + ... + 3551.

It is an arithmetic number, because the mean of its divisors is an integer number (110688).

2⁶⁴³²⁸¹ is an apocalyptic number.

It is an amenable number.

643281 is a deficient number, since it is larger than the sum of its proper divisors (242223).

643281 is a wasteful number, since it uses less digits than its factorization.

643281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6951.

The product of its digits is 1152, while the sum is 24.

The square root of 643281 is about 802.0480035509. The cubic root of 643281 is about 86.3244012497.

The spelling of 643281 in words is "six hundred forty-three thousand, two hundred eighty-one".