1664266777 has 2 divisors, whose sum is σ = 1664266778. Its totient is φ = 1664266776.

The previous prime is 1664266763. The next prime is 1664266831. The reversal of 1664266777 is 7776624661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1152195136 + 512071641 = 33944^2 + 22629^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664266777 - 2⁷ = 1664266649 is a prime.

It is not a weakly prime, because it can be changed into another prime (1664261777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832133388 + 832133389.

It is an arithmetic number, because the mean of its divisors is an integer number (832133389).

Almost surely, 2^1664266777 is an apocalyptic number.

It is an amenable number.

1664266777 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664266777 is an equidigital number, since it uses as much as digits as its factorization.

1664266777 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3556224, while the sum is 52.

The square root of 1664266777 is about 40795.4259323273. The cubic root of 1664266777 is about 1185.0617513679.

The spelling of 1664266777 in words is "one billion, six hundred sixty-four million, two hundred sixty-six thousand, seven hundred seventy-seven".