1664039989 has 2 divisors, whose sum is σ = 1664039990. Its totient is φ = 1664039988.

The previous prime is 1664039987. The next prime is 1664040011. The reversal of 1664039989 is 9899304661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1343808964 + 320231025 = 36658^2 + 17895^2 .

It is an emirp because it is prime and its reverse (9899304661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1664039989 - 2¹ = 1664039987 is a prime.

It is a super-2 number, since 2×1664039989² = 5538058169982240242, which contains 22 as substring.

Together with 1664039987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664039983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832019994 + 832019995.

It is an arithmetic number, because the mean of its divisors is an integer number (832019995).

Almost surely, 2^1664039989 is an apocalyptic number.

It is an amenable number.

1664039989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664039989 is an equidigital number, since it uses as much as digits as its factorization.

1664039989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2519424, while the sum is 55.

The square root of 1664039989 is about 40792.6462613055. The cubic root of 1664039989 is about 1185.0079198554.

The spelling of 1664039989 in words is "one billion, six hundred sixty-four million, thirty-nine thousand, nine hundred eighty-nine".