647788961 has 8 divisors (see below), whose sum is σ = 688744584. Its totient is φ = 607150080.

The previous prime is 647788931. The next prime is 647788963. The reversal of 647788961 is 169887746.

647788961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 362178961 + 285610000 = 19031^2 + 16900^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 647788961 - 2¹⁴ = 647772577 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 647788897 and 647788906.

It is not an unprimeable number, because it can be changed into a prime (647788963) 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, 74960 + ... + 83153.

It is an arithmetic number, because the mean of its divisors is an integer number (86093073).

Almost surely, 2^647788961 is an apocalyptic number.

It is an amenable number.

647788961 is a deficient number, since it is larger than the sum of its proper divisors (40955623).

647788961 is a wasteful number, since it uses less digits than its factorization.

647788961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158371.

The product of its digits is 4064256, while the sum is 56.

The square root of 647788961 is about 25451.6985877171. The cubic root of 647788961 is about 865.2557903464.

The spelling of 647788961 in words is "six hundred forty-seven million, seven hundred eighty-eight thousand, nine hundred sixty-one".