661739521297 has 2 divisors, whose sum is σ = 661739521298. Its totient is φ = 661739521296.

The previous prime is 661739521271. The next prime is 661739521327. The reversal of 661739521297 is 792125937166.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 457366811521 + 204372709776 = 676289^2 + 452076^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661739521297 is a prime.

It is not a weakly prime, because it can be changed into another prime (661739521697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330869760648 + 330869760649.

It is an arithmetic number, because the mean of its divisors is an integer number (330869760649).

Almost surely, 2^661739521297 is an apocalyptic number.

It is an amenable number.

661739521297 is a deficient number, since it is larger than the sum of its proper divisors (1).

661739521297 is an equidigital number, since it uses as much as digits as its factorization.

661739521297 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8573040, while the sum is 58.

The spelling of 661739521297 in words is "six hundred sixty-one billion, seven hundred thirty-nine million, five hundred twenty-one thousand, two hundred ninety-seven".