643400 has 24 divisors (see below), whose sum is σ = 1496370. Its totient is φ = 257280.

The previous prime is 643373. The next prime is 643403. The reversal of 643400 is 4346.

It can be written as a sum of positive squares in 3 ways, for example, as 586756 + 56644 = 766^2 + 238^2 .

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (643403) by changing a digit.

643400 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 5 ways as a sum of consecutive naturals, for example, 1409 + ... + 1808.

2⁶⁴³⁴⁰⁰ is an apocalyptic number.

It is an amenable number.

643400 is an abundant number, since it is smaller than the sum of its proper divisors (852970).

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

643400 is a wasteful number, since it uses less digits than its factorization.

643400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3233 (or 3224 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 643400 is about 802.1221852062. The cubic root of 643400 is about 86.3297239472.

Adding to 643400 its reverse (4346), we get a palindrome (647746).

The spelling of 643400 in words is "six hundred forty-three thousand, four hundred".