647257728 has 256 divisors, whose sum is σ = 2035756800. Its totient is φ = 180289536.

The previous prime is 647257717. The next prime is 647257729. The reversal of 647257728 is 827752746.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (647257729) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2460925 + ... + 2461187.

It is an arithmetic number, because the mean of its divisors is an integer number (7952175).

Almost surely, 2^647257728 is an apocalyptic number.

647257728 is a gapful number since it is divisible by the number (68) 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 647257728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1017878400).

647257728 is an abundant number, since it is smaller than the sum of its proper divisors (1388499072).

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

647257728 is a wasteful number, since it uses less digits than its factorization.

647257728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 339 (or 327 counting only the distinct ones).

The product of its digits is 1317120, while the sum is 48.

The square root of 647257728 is about 25441.2603461385. The cubic root of 647257728 is about 865.0192019082.

The spelling of 647257728 in words is "six hundred forty-seven million, two hundred fifty-seven thousand, seven hundred twenty-eight".