665531420 has 24 divisors (see below), whose sum is σ = 1411458048. Its totient is φ = 263576000.

The previous prime is 665531407. The next prime is 665531429. The reversal of 665531420 is 24135566.

665531420 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665531429) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 162716 + ... + 166755.

It is an arithmetic number, because the mean of its divisors is an integer number (58810752).

Almost surely, 2^665531420 is an apocalyptic number.

It is an amenable number.

665531420 is an abundant number, since it is smaller than the sum of its proper divisors (745926628).

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

665531420 is a wasteful number, since it uses less digits than its factorization.

665531420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329581 (or 329579 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 32.

The square root of 665531420 is about 25797.8956506146. The cubic root of 665531420 is about 873.0843183500.

Adding to 665531420 its reverse (24135566), we get a palindrome (689666986).

The spelling of 665531420 in words is "six hundred sixty-five million, five hundred thirty-one thousand, four hundred twenty".