642733728 has 384 divisors, whose sum is σ = 2235340800. Its totient is φ = 157151232.

The previous prime is 642733727. The next prime is 642733733. The reversal of 642733728 is 827337246.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 642733728.

It is not an unprimeable number, because it can be changed into a prime (642733727) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 10893763 + ... + 10893821.

It is an arithmetic number, because the mean of its divisors is an integer number (5821200).

Almost surely, 2^642733728 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 642733728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1117670400).

642733728 is an abundant number, since it is smaller than the sum of its proper divisors (1592607072).

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

642733728 is a wasteful number, since it uses less digits than its factorization.

642733728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164 (or 156 counting only the distinct ones).

The product of its digits is 338688, while the sum is 42.

The square root of 642733728 is about 25352.1937512319. The cubic root of 642733728 is about 862.9991411199. Note that the first 3 decimals are identical.

The spelling of 642733728 in words is "six hundred forty-two million, seven hundred thirty-three thousand, seven hundred twenty-eight".