661874242121 has 2 divisors, whose sum is σ = 661874242122. Its totient is φ = 661874242120.

The previous prime is 661874242111. The next prime is 661874242181. The reversal of 661874242121 is 121242478166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 564317966521 + 97556275600 = 751211^2 + 312340^2 .

It is a cyclic number.

It is not a de Polignac number, because 661874242121 - 2¹⁴ = 661874225737 is a prime.

It is not a weakly prime, because it can be changed into another prime (661874242111) 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, 330937121060 + 330937121061.

It is an arithmetic number, because the mean of its divisors is an integer number (330937121061).

Almost surely, 2^661874242121 is an apocalyptic number.

It is an amenable number.

661874242121 is a deficient number, since it is larger than the sum of its proper divisors (1).

661874242121 is an equidigital number, since it uses as much as digits as its factorization.

661874242121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 258048, while the sum is 44.

The spelling of 661874242121 in words is "six hundred sixty-one billion, eight hundred seventy-four million, two hundred forty-two thousand, one hundred twenty-one".