664189 has 4 divisors (see below), whose sum is σ = 665820. Its totient is φ = 662560.

The previous prime is 664177. The next prime is 664193. The reversal of 664189 is 981466.

664189 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 981466 = 2 ⋅490733.

It can be written as a sum of positive squares in 2 ways, for example, as 396900 + 267289 = 630^2 + 517^2 .

It is a cyclic number.

It is not a de Polignac number, because 664189 - 2⁷ = 664061 is a prime.

It is a super-2 number, since 2×664189² = 882294055442, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664109) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 399 + ... + 1219.

It is an arithmetic number, because the mean of its divisors is an integer number (166455).

2⁶⁶⁴¹⁸⁹ is an apocalyptic number.

It is an amenable number.

664189 is a deficient number, since it is larger than the sum of its proper divisors (1631).

664189 is an equidigital number, since it uses as much as digits as its factorization.

664189 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1630.

The product of its digits is 10368, while the sum is 34.

The square root of 664189 is about 814.9779138112. The cubic root of 664189 is about 87.2496900671.

The spelling of 664189 in words is "six hundred sixty-four thousand, one hundred eighty-nine".