66505331261 has 2 divisors, whose sum is σ = 66505331262. Its totient is φ = 66505331260.

The previous prime is 66505331251. The next prime is 66505331311. The reversal of 66505331261 is 16213350566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 60393062500 + 6112268761 = 245750^2 + 78181^2 .

It is a cyclic number.

It is not a de Polignac number, because 66505331261 - 2²² = 66501136957 is a prime.

It is a super-2 number, since 2×66505331261² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66505331231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33252665630 + 33252665631.

It is an arithmetic number, because the mean of its divisors is an integer number (33252665631).

Almost surely, 2^66505331261 is an apocalyptic number.

It is an amenable number.

66505331261 is a deficient number, since it is larger than the sum of its proper divisors (1).

66505331261 is an equidigital number, since it uses as much as digits as its factorization.

66505331261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 97200, while the sum is 38.

The spelling of 66505331261 in words is "sixty-six billion, five hundred five million, three hundred thirty-one thousand, two hundred sixty-one".