647137561 has 6 divisors (see below), whose sum is σ = 752792730. Its totient is φ = 554689296.

The previous prime is 647137559. The next prime is 647137577. The reversal of 647137561 is 165731746.

It can be written as a sum of positive squares in only one way, i.e., 637865536 + 9272025 = 25256^2 + 3045^2 .

It is not a de Polignac number, because 647137561 - 2¹ = 647137559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (647137061) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6603396 + ... + 6603493.

It is an arithmetic number, because the mean of its divisors is an integer number (125465455).

Almost surely, 2^647137561 is an apocalyptic number.

It is an amenable number.

647137561 is a deficient number, since it is larger than the sum of its proper divisors (105655169).

647137561 is a wasteful number, since it uses less digits than its factorization.

647137561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13206903 (or 13206896 counting only the distinct ones).

The product of its digits is 105840, while the sum is 40.

The square root of 647137561 is about 25438.8985807169. The cubic root of 647137561 is about 864.9656667184.

The spelling of 647137561 in words is "six hundred forty-seven million, one hundred thirty-seven thousand, five hundred sixty-one".