191978657361 has 14 divisors (see below), whose sum is σ = 287836314530. Its totient is φ = 127985771088.

The previous prime is 191978657341. The next prime is 191978657393. The reversal of 191978657361 is 163756879191.

191978657361 is a `hidden beast` number, since 1 + 9 + 197 + 86 + 5 + 7 + 361 = 666.

191978657361 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 177477680961 + 14500976400 = 421281^2 + 120420^2 .

It is not a de Polignac number, because 191978657361 - 2¹³ = 191978649169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191978657341) 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 in 13 ways as a sum of consecutive naturals, for example, 131671876 + ... + 131673333.

Almost surely, 2^191978657361 is an apocalyptic number.

It is an amenable number.

191978657361 is a deficient number, since it is larger than the sum of its proper divisors (95857657169).

191978657361 is an frugal number, since it uses more digits than its factorization.

191978657361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263345227 (or 263345212 counting only the distinct ones).

The product of its digits is 17146080, while the sum is 63.

The spelling of 191978657361 in words is "one hundred ninety-one billion, nine hundred seventy-eight million, six hundred fifty-seven thousand, three hundred sixty-one".