647640445 has 4 divisors (see below), whose sum is σ = 777168540. Its totient is φ = 518112352.

The previous prime is 647640431. The next prime is 647640481. The reversal of 647640445 is 544046746.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 355435609 + 292204836 = 18853^2 + 17094^2 .

It is a cyclic number.

It is not a de Polignac number, because 647640445 - 2⁹ = 647639933 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 647640398 and 647640407.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64764040 + ... + 64764049.

It is an arithmetic number, because the mean of its divisors is an integer number (194292135).

Almost surely, 2^647640445 is an apocalyptic number.

It is an amenable number.

647640445 is a deficient number, since it is larger than the sum of its proper divisors (129528095).

647640445 is a wasteful number, since it uses less digits than its factorization.

647640445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129528094.

The product of its (nonzero) digits is 322560, while the sum is 40.

The square root of 647640445 is about 25448.7808155911. The cubic root of 647640445 is about 865.1896607072.

The spelling of 647640445 in words is "six hundred forty-seven million, six hundred forty thousand, four hundred forty-five".