643465728 has 160 divisors (see below), whose sum is σ = 1929787200. Its totient is φ = 211673088.

The previous prime is 643465721. The next prime is 643465747. The reversal of 643465728 is 827564346.

It is a super-2 number, since 2×643465728² = 828096286221139968, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (643465721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1230075 + ... + 1230597.

It is an arithmetic number, because the mean of its divisors is an integer number (12061170).

Almost surely, 2^643465728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643465728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (964893600).

643465728 is an abundant number, since it is smaller than the sum of its proper divisors (1286321472).

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

643465728 is an equidigital number, since it uses as much as digits as its factorization.

643465728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639 (or 617 counting only the distinct ones).

The product of its digits is 967680, while the sum is 45.

The square root of 643465728 is about 25366.6262636560. The cubic root of 643465728 is about 863.3266358393.

The spelling of 643465728 in words is "six hundred forty-three million, four hundred sixty-five thousand, seven hundred twenty-eight".