647568981 has 12 divisors (see below), whose sum is σ = 990399852. Its totient is φ = 406317696.

The previous prime is 647568967. The next prime is 647568989. The reversal of 647568981 is 189865746.

647568981 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 2 ways, for example, as 521208900 + 126360081 = 22830^2 + 11241^2 .

It is not a de Polignac number, because 647568981 - 2¹⁴ = 647552597 is a prime.

It is a super-2 number, since 2×647568981² = 838691170306756722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647568989) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2116086 + ... + 2116391.

It is an arithmetic number, because the mean of its divisors is an integer number (82533321).

Almost surely, 2^647568981 is an apocalyptic number.

It is an amenable number.

647568981 is a deficient number, since it is larger than the sum of its proper divisors (342830871).

647568981 is a wasteful number, since it uses less digits than its factorization.

647568981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4232500 (or 4232497 counting only the distinct ones).

The product of its digits is 2903040, while the sum is 54.

The square root of 647568981 is about 25447.3767017349. The cubic root of 647568981 is about 865.1578363677.

It can be divided in two parts, 64756 and 8981, that added together give a palindrome (73737).

The spelling of 647568981 in words is "six hundred forty-seven million, five hundred sixty-eight thousand, nine hundred eighty-one".