665879220 has 36 divisors (see below), whose sum is σ = 2019834180. Its totient is φ = 177567744.

The previous prime is 665879213. The next prime is 665879231. The reversal of 665879220 is 22978566.

665879220 is a `hidden beast` number, since 66 + 587 + 9 + 2 + 2 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 193599396 + 472279824 = 13914^2 + 21732^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1849485 + ... + 1849844.

It is an arithmetic number, because the mean of its divisors is an integer number (56106505).

Almost surely, 2^665879220 is an apocalyptic number.

665879220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665879220 is an abundant number, since it is smaller than the sum of its proper divisors (1353954960).

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

665879220 is a wasteful number, since it uses less digits than its factorization.

665879220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3699344 (or 3699339 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The square root of 665879220 is about 25804.6356300569. The cubic root of 665879220 is about 873.2363802141.

The spelling of 665879220 in words is "six hundred sixty-five million, eight hundred seventy-nine thousand, two hundred twenty".