391983943661 has 2 divisors, whose sum is σ = 391983943662. Its totient is φ = 391983943660.

The previous prime is 391983943601. The next prime is 391983943691. The reversal of 391983943661 is 166349389193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 213253698436 + 178730245225 = 461794^2 + 422765^2 .

It is a cyclic number.

It is not a de Polignac number, because 391983943661 - 2²⁶ = 391916834797 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 391983943594 and 391983943603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391983943601) 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, 195991971830 + 195991971831.

It is an arithmetic number, because the mean of its divisors is an integer number (195991971831).

Almost surely, 2^391983943661 is an apocalyptic number.

It is an amenable number.

391983943661 is a deficient number, since it is larger than the sum of its proper divisors (1).

391983943661 is an equidigital number, since it uses as much as digits as its factorization.

391983943661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22674816, while the sum is 62.

The spelling of 391983943661 in words is "three hundred ninety-one billion, nine hundred eighty-three million, nine hundred forty-three thousand, six hundred sixty-one".