647607736781 has 2 divisors, whose sum is σ = 647607736782. Its totient is φ = 647607736780.

The previous prime is 647607736777. The next prime is 647607736871. The reversal of 647607736781 is 187637706746.

Together with next prime (647607736871) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 641054834281 + 6552902500 = 800659^2 + 80950^2 .

It is a cyclic number.

It is not a de Polignac number, because 647607736781 - 2² = 647607736777 is a prime.

It is a super-2 number, since 2×647607736781² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647607736771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323803868390 + 323803868391.

It is an arithmetic number, because the mean of its divisors is an integer number (323803868391).

Almost surely, 2^647607736781 is an apocalyptic number.

It is an amenable number.

647607736781 is a deficient number, since it is larger than the sum of its proper divisors (1).

647607736781 is an equidigital number, since it uses as much as digits as its factorization.

647607736781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 49787136, while the sum is 62.

The spelling of 647607736781 in words is "six hundred forty-seven billion, six hundred seven million, seven hundred thirty-six thousand, seven hundred eighty-one".