66561477727 has 2 divisors, whose sum is σ = 66561477728. Its totient is φ = 66561477726.

The previous prime is 66561477721. The next prime is 66561477743. The reversal of 66561477727 is 72777416566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66561477727 - 2¹⁵ = 66561444959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66561477721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33280738863 + 33280738864.

It is an arithmetic number, because the mean of its divisors is an integer number (33280738864).

Almost surely, 2^66561477727 is an apocalyptic number.

66561477727 is a deficient number, since it is larger than the sum of its proper divisors (1).

66561477727 is an equidigital number, since it uses as much as digits as its factorization.

66561477727 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20744640, while the sum is 58.

The spelling of 66561477727 in words is "sixty-six billion, five hundred sixty-one million, four hundred seventy-seven thousand, seven hundred twenty-seven".