817785238661 has 2 divisors, whose sum is σ = 817785238662. Its totient is φ = 817785238660.

The previous prime is 817785238657. The next prime is 817785238709. The reversal of 817785238661 is 166832587718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 817098484225 + 686754436 = 903935^2 + 26206^2 .

It is a cyclic number.

It is not a de Polignac number, because 817785238661 - 2² = 817785238657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 817785238594 and 817785238603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (817785231661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408892619330 + 408892619331.

It is an arithmetic number, because the mean of its divisors is an integer number (408892619331).

Almost surely, 2^817785238661 is an apocalyptic number.

It is an amenable number.

817785238661 is a deficient number, since it is larger than the sum of its proper divisors (1).

817785238661 is an equidigital number, since it uses as much as digits as its factorization.

817785238661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27095040, while the sum is 62.

The spelling of 817785238661 in words is "eight hundred seventeen billion, seven hundred eighty-five million, two hundred thirty-eight thousand, six hundred sixty-one".