647768128 has 112 divisors (see below), whose sum is σ = 1542775680. Its totient is φ = 263983104.

The previous prime is 647768123. The next prime is 647768131. The reversal of 647768128 is 821867746.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (112).

It is not an unprimeable number, because it can be changed into a prime (647768123) 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, 948075 + ... + 948757.

Almost surely, 2^647768128 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 647768128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (771387840).

647768128 is an abundant number, since it is smaller than the sum of its proper divisors (895007552).

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

647768128 is a wasteful number, since it uses less digits than its factorization.

647768128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804 (or 794 counting only the distinct ones).

The product of its digits is 903168, while the sum is 49.

The square root of 647768128 is about 25451.2893190109. The cubic root of 647768128 is about 865.2465146572.

The spelling of 647768128 in words is "six hundred forty-seven million, seven hundred sixty-eight thousand, one hundred twenty-eight".