1665869 has 2 divisors, whose sum is σ = 1665870. Its totient is φ = 1665868.

The previous prime is 1665841. The next prime is 1665877. The reversal of 1665869 is 9685661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1532644 + 133225 = 1238^2 + 365^2 .

It is an emirp because it is prime and its reverse (9685661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1665869 - 2²⁰ = 617293 is a prime.

It is a super-2 number, since 2×1665869² = 5550239050322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1665889) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832934 + 832935.

It is an arithmetic number, because the mean of its divisors is an integer number (832935).

2^1665869 is an apocalyptic number.

It is an amenable number.

1665869 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665869 is an equidigital number, since it uses as much as digits as its factorization.

1665869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 41.

The square root of 1665869 is about 1290.6854767913. The cubic root of 1665869 is about 118.5441923632.

The spelling of 1665869 in words is "one million, six hundred sixty-five thousand, eight hundred sixty-nine".