666438 has 16 divisors (see below), whose sum is σ = 1376256. Its totient is φ = 214920.

The previous prime is 666437. The next prime is 666439. The reversal of 666438 is 834666.

It is an interprime number because it is at equal distance from previous prime (666437) and next prime (666439).

It is a junction number, because it is equal to n+sod(n) for n = 666399 and 666408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1606 + ... + 1977.

It is an arithmetic number, because the mean of its divisors is an integer number (86016).

2⁶⁶⁶⁴³⁸ is an apocalyptic number.

666438 is an abundant number, since it is smaller than the sum of its proper divisors (709818).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666438 is a wasteful number, since it uses less digits than its factorization.

666438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3619.

The product of its digits is 20736, while the sum is 33.

The square root of 666438 is about 816.3565397545. The cubic root of 666438 is about 87.3480573948.

The spelling of 666438 in words is "six hundred sixty-six thousand, four hundred thirty-eight".