1666691664 has 40 divisors (see below), whose sum is σ = 4697041632. Its totient is φ = 505057920.

The previous prime is 1666691659. The next prime is 1666691671. The reversal of 1666691664 is 4661966661.

It is a super-2 number, since 2×1666691664² = 5555722205694177792, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1577779 + ... + 1578834.

Almost surely, 2^1666691664 is an apocalyptic number.

It is an amenable number.

1666691664 is an abundant number, since it is smaller than the sum of its proper divisors (3030349968).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1666691664 is a wasteful number, since it uses less digits than its factorization.

1666691664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3156635 (or 3156629 counting only the distinct ones).

The product of its digits is 1679616, while the sum is 51.

The square root of 1666691664 is about 40825.1351987963. The cubic root of 1666691664 is about 1185.6370289902.

The spelling of 1666691664 in words is "one billion, six hundred sixty-six million, six hundred ninety-one thousand, six hundred sixty-four".