647663761 has 2 divisors, whose sum is σ = 647663762. Its totient is φ = 647663760.

The previous prime is 647663759. The next prime is 647663791. The reversal of 647663761 is 167366746.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 591413761 + 56250000 = 24319^2 + 7500^2 .

It is a cyclic number.

It is not a de Polignac number, because 647663761 - 2¹ = 647663759 is a prime.

Together with 647663759, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (647663791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323831880 + 323831881.

It is an arithmetic number, because the mean of its divisors is an integer number (323831881).

Almost surely, 2^647663761 is an apocalyptic number.

It is an amenable number.

647663761 is a deficient number, since it is larger than the sum of its proper divisors (1).

647663761 is an equidigital number, since it uses as much as digits as its factorization.

647663761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 762048, while the sum is 46.

The square root of 647663761 is about 25449.2389080695. The cubic root of 647663761 is about 865.2000432789.

The spelling of 647663761 in words is "six hundred forty-seven million, six hundred sixty-three thousand, seven hundred sixty-one".