668431 has 4 divisors (see below), whose sum is σ = 670072. Its totient is φ = 666792.

The previous prime is 668417. The next prime is 668471. The reversal of 668431 is 134866.

668431 is nontrivially palindromic in base 3.

668431 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: 134866 = 2 ⋅67433.

It is a 3-Lehmer number, since φ(668431) divides (668431-1)³.

It is a cyclic number.

It is not a de Polignac number, because 668431 - 2⁷ = 668303 is a prime.

It is a super-2 number, since 2×668431² = 893600003522, which contains 22 as substring.

It is a Duffinian number.

668431 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 668431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668471) 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, 316 + ... + 1198.

It is an arithmetic number, because the mean of its divisors is an integer number (167518).

2⁶⁶⁸⁴³¹ is an apocalyptic number.

668431 is a deficient number, since it is larger than the sum of its proper divisors (1641).

668431 is an equidigital number, since it uses as much as digits as its factorization.

668431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1640.

The product of its digits is 3456, while the sum is 28.

The square root of 668431 is about 817.5762961339. The cubic root of 668431 is about 87.4350429465.

The spelling of 668431 in words is "six hundred sixty-eight thousand, four hundred thirty-one".