1664444661 has 24 divisors (see below), whose sum is σ = 2441688480. Its totient is φ = 1007788320.

The previous prime is 1664444659. The next prime is 1664444689.

1664444661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1664444661 - 2¹ = 1664444659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664444161) 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 in 23 ways as a sum of consecutive naturals, for example, 619026 + ... + 621708.

It is an arithmetic number, because the mean of its divisors is an integer number (101737020).

Almost surely, 2^1664444661 is an apocalyptic number.

1664444661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1664444661 is a deficient number, since it is larger than the sum of its proper divisors (777243819).

1664444661 is a wasteful number, since it uses less digits than its factorization.

1664444661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4417 (or 4406 counting only the distinct ones).

The product of its digits is 331776, while the sum is 42.

The square root of 1664444661 is about 40797.6060694742. The cubic root of 1664444661 is about 1185.1039713648.

The spelling of 1664444661 in words is "one billion, six hundred sixty-four million, four hundred forty-four thousand, six hundred sixty-one".