643450860 has 144 divisors (see below), whose sum is σ = 2127906144. Its totient is φ = 156432384.

The previous prime is 643450853. The next prime is 643450861. The reversal of 643450860 is 68054346.

643450860 is a `hidden beast` number, since 64 + 34 + 508 + 60 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (643450861) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 192564 + ... + 195876.

It is an arithmetic number, because the mean of its divisors is an integer number (14777126).

Almost surely, 2^643450860 is an apocalyptic number.

643450860 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 643450860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1063953072).

643450860 is an abundant number, since it is smaller than the sum of its proper divisors (1484455284).

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

643450860 is a wasteful number, since it uses less digits than its factorization.

643450860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3424 (or 3419 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 643450860 is about 25366.3331997354. Note that the first 3 decimals coincide. The cubic root of 643450860 is about 863.3199864102.

The spelling of 643450860 in words is "six hundred forty-three million, four hundred fifty thousand, eight hundred sixty".