647645816 has 8 divisors (see below), whose sum is σ = 1214335920. Its totient is φ = 323822904.

The previous prime is 647645813. The next prime is 647645839. The reversal of 647645816 is 618546746.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647645813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40477856 + ... + 40477871.

It is an arithmetic number, because the mean of its divisors is an integer number (151791990).

Almost surely, 2^647645816 is an apocalyptic number.

It is an amenable number.

647645816 is a deficient number, since it is larger than the sum of its proper divisors (566690104).

647645816 is a wasteful number, since it uses less digits than its factorization.

647645816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80955733 (or 80955729 counting only the distinct ones).

The product of its digits is 967680, while the sum is 47.

The square root of 647645816 is about 25448.8863410563. The cubic root of 647645816 is about 865.1920524257.

The spelling of 647645816 in words is "six hundred forty-seven million, six hundred forty-five thousand, eight hundred sixteen".