643605870 has 16 divisors (see below), whose sum is σ = 1544654160. Its totient is φ = 171628224.

The previous prime is 643605863. The next prime is 643605877. The reversal of 643605870 is 78506346.

It is an interprime number because it is at equal distance from previous prime (643605863) and next prime (643605877).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643605877) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10726735 + ... + 10726794.

It is an arithmetic number, because the mean of its divisors is an integer number (96540885).

Almost surely, 2^643605870 is an apocalyptic number.

643605870 is an abundant number, since it is smaller than the sum of its proper divisors (901048290).

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

643605870 is a wasteful number, since it uses less digits than its factorization.

643605870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21453539.

The product of its (nonzero) digits is 120960, while the sum is 39.

The square root of 643605870 is about 25369.3884435554. The cubic root of 643605870 is about 863.3893066410.

The spelling of 643605870 in words is "six hundred forty-three million, six hundred five thousand, eight hundred seventy".