1664664661 has 8 divisors (see below), whose sum is σ = 1820216448. Its totient is φ = 1509816000.

The previous prime is 1664664643. The next prime is 1664664671.

1664664661 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-1664664661 is a prime.

It is a super-2 number, since 2×1664664661² = 5542216867164489842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664664671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 170820 + ... + 180301.

It is an arithmetic number, because the mean of its divisors is an integer number (227527056).

Almost surely, 2^1664664661 is an apocalyptic number.

1664664661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1664664661 is a deficient number, since it is larger than the sum of its proper divisors (155551787).

1664664661 is a wasteful number, since it uses less digits than its factorization.

1664664661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 351563.

The product of its digits is 746496, while the sum is 46.

The square root of 1664664661 is about 40800.3022170180. The cubic root of 1664664661 is about 1185.1561832513.

The spelling of 1664664661 in words is "one billion, six hundred sixty-four million, six hundred sixty-four thousand, six hundred sixty-one".