1664581669 has 2 divisors, whose sum is σ = 1664581670. Its totient is φ = 1664581668.

The previous prime is 1664581651. The next prime is 1664581739. The reversal of 1664581669 is 9661854661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1652422500 + 12159169 = 40650^2 + 3487^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664581669 - 2¹⁵ = 1664548901 is a prime.

It is a super-2 number, since 2×1664581669² = 5541664265541651122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664581169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832290834 + 832290835.

It is an arithmetic number, because the mean of its divisors is an integer number (832290835).

Almost surely, 2^1664581669 is an apocalyptic number.

It is an amenable number.

1664581669 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664581669 is an equidigital number, since it uses as much as digits as its factorization.

1664581669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1866240, while the sum is 52.

The square root of 1664581669 is about 40799.2851530514. The cubic root of 1664581669 is about 1185.1364875695.

The spelling of 1664581669 in words is "one billion, six hundred sixty-four million, five hundred eighty-one thousand, six hundred sixty-nine".