643860 has 108 divisors (see below), whose sum is σ = 2303028. Its totient is φ = 145152.

The previous prime is 643859. The next prime is 643873. The reversal of 643860 is 68346.

It can be written as a sum of positive squares in 2 ways, for example, as 298116 + 345744 = 546^2 + 588^2 .

It is a super-3 number, since 3×643860³ = 800747498233368000, which contains 333 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 7.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 8784 + ... + 8856.

2⁶⁴³⁸⁶⁰ is an apocalyptic number.

643860 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1151514).

643860 is an abundant number, since it is smaller than the sum of its proper divisors (1659168).

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

643860 is a wasteful number, since it uses less digits than its factorization.

643860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 643860 is about 802.4088733308. The cubic root of 643860 is about 86.3502929104.

The spelling of 643860 in words is "six hundred forty-three thousand, eight hundred sixty".