197561548781 has 2 divisors, whose sum is σ = 197561548782. Its totient is φ = 197561548780.

The previous prime is 197561548763. The next prime is 197561548813. The reversal of 197561548781 is 187845165791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 111105555625 + 86455993156 = 333325^2 + 294034^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-197561548781 is a prime.

It is a super-2 number, since 2×197561548781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (197561548721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98780774390 + 98780774391.

It is an arithmetic number, because the mean of its divisors is an integer number (98780774391).

Almost surely, 2^197561548781 is an apocalyptic number.

It is an amenable number.

197561548781 is a deficient number, since it is larger than the sum of its proper divisors (1).

197561548781 is an equidigital number, since it uses as much as digits as its factorization.

197561548781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16934400, while the sum is 62.

The spelling of 197561548781 in words is "one hundred ninety-seven billion, five hundred sixty-one million, five hundred forty-eight thousand, seven hundred eighty-one".