1666886661 has 32 divisors (see below), whose sum is σ = 2703680640. Its totient is φ = 1006588800.

The previous prime is 1666886657. The next prime is 1666886681.

1666886661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1666886661 - 2² = 1666886657 is a prime.

It is a super-2 number, since 2×1666886661² = 5557022281239457842, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1666886598 and 1666886607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666886681) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 73471 + ... + 93443.

It is an arithmetic number, because the mean of its divisors is an integer number (84490020).

Almost surely, 2^1666886661 is an apocalyptic number.

1666886661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1666886661 is a deficient number, since it is larger than the sum of its proper divisors (1036793979).

1666886661 is a wasteful number, since it uses less digits than its factorization.

1666886661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20274 (or 20268 counting only the distinct ones).

The product of its digits is 2985984, while the sum is 54.

The square root of 1666886661 is about 40827.5233267951. The cubic root of 1666886661 is about 1185.6832656263.

The spelling of 1666886661 in words is "one billion, six hundred sixty-six million, eight hundred eighty-six thousand, six hundred sixty-one".