647665636 has 24 divisors (see below), whose sum is σ = 1155672504. Its totient is φ = 317525760.

The previous prime is 647665633. The next prime is 647665693. The reversal of 647665636 is 636566746.

It can be written as a sum of positive squares in 4 ways, for example, as 94945536 + 552720100 = 9744^2 + 23510^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 647665636.

It is not an unprimeable number, because it can be changed into a prime (647665633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44106 + ... + 56926.

It is an arithmetic number, because the mean of its divisors is an integer number (48153021).

Almost surely, 2^647665636 is an apocalyptic number.

It is an amenable number.

647665636 is a deficient number, since it is larger than the sum of its proper divisors (508006868).

647665636 is a wasteful number, since it uses less digits than its factorization.

647665636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13071 (or 13069 counting only the distinct ones).

The product of its digits is 3265920, while the sum is 49.

The square root of 647665636 is about 25449.2757460797. The cubic root of 647665636 is about 865.2008782021.

The spelling of 647665636 in words is "six hundred forty-seven million, six hundred sixty-five thousand, six hundred thirty-six".