666603 has 16 divisors (see below), whose sum is σ = 1128960. Its totient is φ = 380808.

The previous prime is 666599. The next prime is 666607. The reversal of 666603 is 306666.

It is an interprime number because it is at equal distance from previous prime (666599) and next prime (666607).

It is not a de Polignac number, because 666603 - 2² = 666599 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

666603 is a lucky number.

It is a nialpdrome in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666607) 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, 1575 + ... + 1952.

It is an arithmetic number, because the mean of its divisors is an integer number (70560).

2⁶⁶⁶⁶⁰³ is an apocalyptic number.

666603 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

666603 is a deficient number, since it is larger than the sum of its proper divisors (462357).

666603 is a wasteful number, since it uses less digits than its factorization.

666603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3543 (or 3537 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 27.

The square root of 666603 is about 816.4575922851. The cubic root of 666603 is about 87.3552654873.

The spelling of 666603 in words is "six hundred sixty-six thousand, six hundred three".