666620 has 12 divisors (see below), whose sum is σ = 1399944. Its totient is φ = 266640.

The previous prime is 666607. The next prime is 666637. The reversal of 666620 is 26666.

It is a nialpdrome in base 7 and base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 666620.

It is a congruent number.

It is an unprimeable number.

666620 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16646 + ... + 16685.

It is an arithmetic number, because the mean of its divisors is an integer number (116662).

2⁶⁶⁶⁶²⁰ is an apocalyptic number.

It is an amenable number.

666620 is an abundant number, since it is smaller than the sum of its proper divisors (733324).

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

666620 is a wasteful number, since it uses less digits than its factorization.

666620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33340 (or 33338 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 666620 is about 816.4680030473. The cubic root of 666620 is about 87.3560080716.

The spelling of 666620 in words is "six hundred sixty-six thousand, six hundred twenty".