647449661 has 2 divisors, whose sum is σ = 647449662. Its totient is φ = 647449660.

The previous prime is 647449619. The next prime is 647449687. The reversal of 647449661 is 166944746.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 335256100 + 312193561 = 18310^2 + 17669^2 .

It is a cyclic number.

It is not a de Polignac number, because 647449661 - 2⁶ = 647449597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647445661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323724830 + 323724831.

It is an arithmetic number, because the mean of its divisors is an integer number (323724831).

Almost surely, 2^647449661 is an apocalyptic number.

It is an amenable number.

647449661 is a deficient number, since it is larger than the sum of its proper divisors (1).

647449661 is an equidigital number, since it uses as much as digits as its factorization.

647449661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 47.

The square root of 647449661 is about 25445.0321477494. The cubic root of 647449661 is about 865.1046955816.

The spelling of 647449661 in words is "six hundred forty-seven million, four hundred forty-nine thousand, six hundred sixty-one".