647665640 has 64 divisors (see below), whose sum is σ = 1536399360. Its totient is φ = 245352960.

The previous prime is 647665633. The next prime is 647665693. The reversal of 647665640 is 46566746.

It is a junction number, because it is equal to n+sod(n) for n = 647665591 and 647665600.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52724 + ... + 63836.

It is an arithmetic number, because the mean of its divisors is an integer number (24006240).

Almost surely, 2^647665640 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 647665640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (768199680).

647665640 is an abundant number, since it is smaller than the sum of its proper divisors (888733720).

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

647665640 is a wasteful number, since it uses less digits than its factorization.

647665640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11202 (or 11198 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 44.

The square root of 647665640 is about 25449.2758246674. The cubic root of 647665640 is about 865.2008799833.

The spelling of 647665640 in words is "six hundred forty-seven million, six hundred sixty-five thousand, six hundred forty".