820666 has 24 divisors (see below), whose sum is σ = 1556064. Its totient is φ = 315360.

The previous prime is 820657. The next prime is 820679. The reversal of 820666 is 666028.

It is a happy number.

820666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is a nialpdrome in base 7.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11206 + ... + 11278.

It is an arithmetic number, because the mean of its divisors is an integer number (64836).

2⁸²⁰⁶⁶⁶ is an apocalyptic number.

820666 is a deficient number, since it is larger than the sum of its proper divisors (735398).

820666 is a wasteful number, since it uses less digits than its factorization.

820666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166 (or 93 counting only the distinct ones).

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

The square root of 820666 is about 905.9061761573. The cubic root of 820666 is about 93.6243495956.

The spelling of 820666 in words is "eight hundred twenty thousand, six hundred sixty-six".