1666889 has 16 divisors (see below), whose sum is σ = 2042880. Its totient is φ = 1328400.

The previous prime is 1666871. The next prime is 1666897. The reversal of 1666889 is 9886661.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1666889 is a prime.

It is a plaindrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (1666589) 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, 10964 + ... + 11114.

It is an arithmetic number, because the mean of its divisors is an integer number (127680).

2^1666889 is an apocalyptic number.

1666889 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1666889 is a deficient number, since it is larger than the sum of its proper divisors (375991).

1666889 is a wasteful number, since it uses less digits than its factorization.

1666889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260.

The product of its digits is 124416, while the sum is 44.

The square root of 1666889 is about 1291.0805551940. The cubic root of 1666889 is about 118.5683820216.

The spelling of 1666889 in words is "one million, six hundred sixty-six thousand, eight hundred eighty-nine".