1664121 has 4 divisors (see below), whose sum is σ = 2218832. Its totient is φ = 1109412.

The previous prime is 1664101. The next prime is 1664123. The reversal of 1664121 is 1214661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1664121 - 2⁹ = 1663609 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1664123) 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 3 ways as a sum of consecutive naturals, for example, 277351 + ... + 277356.

It is an arithmetic number, because the mean of its divisors is an integer number (554708).

2^1664121 is an apocalyptic number.

It is an amenable number.

1664121 is a deficient number, since it is larger than the sum of its proper divisors (554711).

1664121 is an equidigital number, since it uses as much as digits as its factorization.

1664121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554710.

The product of its digits is 288, while the sum is 21.

The square root of 1664121 is about 1290.0081395092. The cubic root of 1664121 is about 118.5027149585.

Subtracting from 1664121 its sum of digits (21), we obtain a square (1664100 = 1290²).

Adding to 1664121 its reverse (1214661), we get a palindrome (2878782).

The spelling of 1664121 in words is "one million, six hundred sixty-four thousand, one hundred twenty-one".