1664444689 has 2 divisors, whose sum is σ = 1664444690. Its totient is φ = 1664444688.

The previous prime is 1664444659. The next prime is 1664444711. The reversal of 1664444689 is 9864444661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1661948289 + 2496400 = 40767^2 + 1580^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664444689 - 2¹³ = 1664436497 is a prime.

It is a super-2 number, since 2×1664444689² = 5540752245480613442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1664444629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832222344 + 832222345.

It is an arithmetic number, because the mean of its divisors is an integer number (832222345).

Almost surely, 2^1664444689 is an apocalyptic number.

It is an amenable number.

1664444689 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664444689 is an equidigital number, since it uses as much as digits as its factorization.

1664444689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3981312, while the sum is 52.

The square root of 1664444689 is about 40797.6064126316. The cubic root of 1664444689 is about 1185.1039780102.

The spelling of 1664444689 in words is "one billion, six hundred sixty-four million, four hundred forty-four thousand, six hundred eighty-nine".