1664994661 has 16 divisors (see below), whose sum is σ = 1881532800. Its totient is φ = 1459460800.

The previous prime is 1664994649. The next prime is 1664994677.

1664994661 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 1664994661 - 2⁷ = 1664994533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1664994599 and 1664994608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664994631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 264531 + ... + 270751.

It is an arithmetic number, because the mean of its divisors is an integer number (117595800).

Almost surely, 2^1664994661 is an apocalyptic number.

1664994661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1664994661 is a deficient number, since it is larger than the sum of its proper divisors (216538139).

1664994661 is a wasteful number, since it uses less digits than its factorization.

1664994661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7100.

The product of its digits is 1679616, while the sum is 52.

The square root of 1664994661 is about 40804.3461043061. The cubic root of 1664994661 is about 1185.2344924565.

The spelling of 1664994661 in words is "one billion, six hundred sixty-four million, nine hundred ninety-four thousand, six hundred sixty-one".