391994282557 has 2 divisors, whose sum is σ = 391994282558. Its totient is φ = 391994282556.

The previous prime is 391994282509. The next prime is 391994282591. The reversal of 391994282557 is 755282499193.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 272728350756 + 119265931801 = 522234^2 + 345349^2 .

It is an emirp because it is prime and its reverse (755282499193) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 391994282557 - 2¹⁹ = 391993758269 is a prime.

It is a super-4 number, since 4×391994282557⁴ (a number of 47 digits) contains 4444 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391994282597) 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, 195997141278 + 195997141279.

It is an arithmetic number, because the mean of its divisors is an integer number (195997141279).

Almost surely, 2^391994282557 is an apocalyptic number.

It is an amenable number.

391994282557 is a deficient number, since it is larger than the sum of its proper divisors (1).

391994282557 is an equidigital number, since it uses as much as digits as its factorization.

391994282557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48988800, while the sum is 64.

The spelling of 391994282557 in words is "three hundred ninety-one billion, nine hundred ninety-four million, two hundred eighty-two thousand, five hundred fifty-seven".