647828640 has 144 divisors (see below), whose sum is σ = 2219968296. Its totient is φ = 172032000.

The previous prime is 647828633. The next prime is 647828647. The reversal of 647828640 is 46828746.

It is an interprime number because it is at equal distance from previous prime (647828633) and next prime (647828647).

It can be written as a sum of positive squares in 4 ways, for example, as 647804304 + 24336 = 25452^2 + 156^2 .

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647828647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 403840 + ... + 405440.

Almost surely, 2^647828640 is an apocalyptic number.

647828640 is a gapful number since it is divisible by the number (60) 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 647828640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1109984148).

647828640 is an abundant number, since it is smaller than the sum of its proper divisors (1572139656).

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

647828640 is a wasteful number, since it uses less digits than its factorization.

647828640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1903 (or 1892 counting only the distinct ones).

The product of its (nonzero) digits is 516096, while the sum is 45.

The square root of 647828640 is about 25452.4780718892. The cubic root of 647828640 is about 865.2734564823.

The spelling of 647828640 in words is "six hundred forty-seven million, eight hundred twenty-eight thousand, six hundred forty".