1664865 has 12 divisors (see below), whose sum is σ = 2885844. Its totient is φ = 887904.

The previous prime is 1664863. The next prime is 1664867. The reversal of 1664865 is 5684661.

1664865 is a `hidden beast` number, since 1 + 6 + 648 + 6 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (1664863) and next prime (1664867).

It can be written as a sum of positive squares in 2 ways, for example, as 938961 + 725904 = 969^2 + 852^2 .

It is not a de Polignac number, because 1664865 - 2¹ = 1664863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1664863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18454 + ... + 18543.

It is an arithmetic number, because the mean of its divisors is an integer number (240487).

2^1664865 is an apocalyptic number.

1664865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1664865 is a deficient number, since it is larger than the sum of its proper divisors (1220979).

1664865 is a wasteful number, since it uses less digits than its factorization.

1664865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37008 (or 37005 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 1664865 is about 1290.2964775585. The cubic root of 1664865 is about 118.5203725055.

The spelling of 1664865 in words is "one million, six hundred sixty-four thousand, eight hundred sixty-five".