643340 has 24 divisors (see below), whose sum is σ = 1422960. Its totient is φ = 243648.

The previous prime is 643303. The next prime is 643369. The reversal of 643340 is 43346.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an Ulam number.

It is an unprimeable number.

643340 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 467 + ... + 1226.

It is an arithmetic number, because the mean of its divisors is an integer number (59290).

2⁶⁴³³⁴⁰ is an apocalyptic number.

It is an amenable number.

643340 is an abundant number, since it is smaller than the sum of its proper divisors (779620).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643340 is a wasteful number, since it uses less digits than its factorization.

643340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1721 (or 1719 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 20.

The square root of 643340 is about 802.0847835485. The cubic root of 643340 is about 86.3270403162.

Adding to 643340 its reverse (43346), we get a palindrome (686686).

The spelling of 643340 in words is "six hundred forty-three thousand, three hundred forty".