1866091 has 2 divisors, whose sum is σ = 1866092. Its totient is φ = 1866090.

The previous prime is 1866083. The next prime is 1866101. The reversal of 1866091 is 1906681.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1866091 - 2³ = 1866083 is a prime.

It is equal to p₁₃₉₆₈₄ and since 1866091 and 139684 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (1866001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 933045 + 933046.

It is an arithmetic number, because the mean of its divisors is an integer number (933046).

2^1866091 is an apocalyptic number.

1866091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1866091 is an equidigital number, since it uses as much as digits as its factorization.

1866091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1866091 is about 1366.0494134547. The cubic root of 1866091 is about 123.1149914992.

The spelling of 1866091 in words is "one million, eight hundred sixty-six thousand, ninety-one".