664723 has 4 divisors (see below), whose sum is σ = 693648. Its totient is φ = 635800.

The previous prime is 664711. The next prime is 664739. The reversal of 664723 is 327466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 327466 = 2 ⋅163733.

It is a cyclic number.

It is not a de Polignac number, because 664723 - 2⁵ = 664691 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 664691 and 664700.

It is not an unprimeable number, because it can be changed into a prime (664793) 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, 14428 + ... + 14473.

It is an arithmetic number, because the mean of its divisors is an integer number (173412).

2⁶⁶⁴⁷²³ is an apocalyptic number.

664723 is a deficient number, since it is larger than the sum of its proper divisors (28925).

664723 is a wasteful number, since it uses less digits than its factorization.

664723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28924.

The product of its digits is 6048, while the sum is 28.

The square root of 664723 is about 815.3054642280. The cubic root of 664723 is about 87.2730663721.

It can be divided in two parts, 6647 and 23, that multiplied together give a square (152881 = 391²).

The spelling of 664723 in words is "six hundred sixty-four thousand, seven hundred twenty-three".