66551777 has 2 divisors, whose sum is σ = 66551778. Its totient is φ = 66551776.

The previous prime is 66551747. The next prime is 66551783. The reversal of 66551777 is 77715566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65918161 + 633616 = 8119^2 + 796^2 .

It is a cyclic number.

It is not a de Polignac number, because 66551777 - 2⁶ = 66551713 is a prime.

It is not a weakly prime, because it can be changed into another prime (66551717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33275888 + 33275889.

It is an arithmetic number, because the mean of its divisors is an integer number (33275889).

Almost surely, 2^66551777 is an apocalyptic number.

It is an amenable number.

66551777 is a deficient number, since it is larger than the sum of its proper divisors (1).

66551777 is an equidigital number, since it uses as much as digits as its factorization.

66551777 is an evil number, because the sum of its binary digits is even.

The product of its digits is 308700, while the sum is 44.

The square root of 66551777 is about 8157.9272490014. The cubic root of 66551777 is about 405.2470717186.

The spelling of 66551777 in words is "sixty-six million, five hundred fifty-one thousand, seven hundred seventy-seven".