391242261973 has 2 divisors, whose sum is σ = 391242261974. Its totient is φ = 391242261972.

The previous prime is 391242261931. The next prime is 391242261983. The reversal of 391242261973 is 379162242193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 357123369604 + 34118892369 = 597598^2 + 184713^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-391242261973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391242261983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195621130986 + 195621130987.

It is an arithmetic number, because the mean of its divisors is an integer number (195621130987).

Almost surely, 2^391242261973 is an apocalyptic number.

It is an amenable number.

391242261973 is a deficient number, since it is larger than the sum of its proper divisors (1).

391242261973 is an equidigital number, since it uses as much as digits as its factorization.

391242261973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 979776, while the sum is 49.

The spelling of 391242261973 in words is "three hundred ninety-one billion, two hundred forty-two million, two hundred sixty-one thousand, nine hundred seventy-three".