647407661 has 2 divisors, whose sum is σ = 647407662. Its totient is φ = 647407660.

The previous prime is 647407637. The next prime is 647407669. The reversal of 647407661 is 166704746.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 538518436 + 108889225 = 23206^2 + 10435^2 .

It is a cyclic number.

It is not a de Polignac number, because 647407661 - 2⁶ = 647407597 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647407669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323703830 + 323703831.

It is an arithmetic number, because the mean of its divisors is an integer number (323703831).

Almost surely, 2^647407661 is an apocalyptic number.

It is an amenable number.

647407661 is a deficient number, since it is larger than the sum of its proper divisors (1).

647407661 is an equidigital number, since it uses as much as digits as its factorization.

647407661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 169344, while the sum is 41.

The square root of 647407661 is about 25444.2068259162. The cubic root of 647407661 is about 865.0859887564.

The spelling of 647407661 in words is "six hundred forty-seven million, four hundred seven thousand, six hundred sixty-one".