661323 has 16 divisors (see below), whose sum is σ = 982016. Its totient is φ = 393120.

The previous prime is 661321. The next prime is 661327. The reversal of 661323 is 323166.

661323 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661323 - 2¹ = 661321 is a prime.

It is a super-2 number, since 2×661323² = 874696220658, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661323.

It is not an unprimeable number, because it can be changed into a prime (661321) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 936 + ... + 1482.

It is an arithmetic number, because the mean of its divisors is an integer number (61376).

2⁶⁶¹³²³ is an apocalyptic number.

661323 is a deficient number, since it is larger than the sum of its proper divisors (320693).

661323 is a wasteful number, since it uses less digits than its factorization.

661323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 594.

The product of its digits is 648, while the sum is 21.

The square root of 661323 is about 813.2176830345. The cubic root of 661323 is about 87.1240139189.

Subtracting from 661323 its product of digits (648), we obtain a triangular number (660675 = T₁₁₄₉).

Adding to 661323 its reverse (323166), we get a palindrome (984489).

The spelling of 661323 in words is "six hundred sixty-one thousand, three hundred twenty-three".