643950 has 72 divisors (see below), whose sum is σ = 1828008. Its totient is φ = 168480.

The previous prime is 643949. The next prime is 643957. The reversal of 643950 is 59346.

It is a happy number.

It is a super-3 number, since 3×643950³ = 801083335289625000, which contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643957) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 12124 + ... + 12176.

It is an arithmetic number, because the mean of its divisors is an integer number (25389).

2⁶⁴³⁹⁵⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643950, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (914004).

643950 is an abundant number, since it is smaller than the sum of its proper divisors (1184058).

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

643950 is a wasteful number, since it uses less digits than its factorization.

643950 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 643950 is about 802.4649525057. The cubic root of 643950 is about 86.3543161268.

It can be divided in two parts, 6 and 43950, that added together give a triangular number (43956 = T₂₉₆).

The spelling of 643950 in words is "six hundred forty-three thousand, nine hundred fifty".