665106820 has 48 divisors (see below), whose sum is σ = 1639411200. Its totient is φ = 221871744.

The previous prime is 665106817. The next prime is 665106877. The reversal of 665106820 is 28601566.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59020 + ... + 69379.

It is an arithmetic number, because the mean of its divisors is an integer number (34154400).

Almost surely, 2^665106820 is an apocalyptic number.

It is an amenable number.

665106820 is an abundant number, since it is smaller than the sum of its proper divisors (974304380).

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

665106820 is a wasteful number, since it uses less digits than its factorization.

665106820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128452 (or 128450 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 665106820 is about 25789.6649842529. The cubic root of 665106820 is about 872.8986068746.

Adding to 665106820 its product of nonzero digits (17280), we get a square (665124100 = 25790²).

The spelling of 665106820 in words is "six hundred sixty-five million, one hundred six thousand, eight hundred twenty".