664400420 has 24 divisors (see below), whose sum is σ = 1396115448. Its totient is φ = 265593600.

The previous prime is 664400389. The next prime is 664400423. The reversal of 664400420 is 24004466.

664400420 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 36096064 + 628304356 = 6008^2 + 25066^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 664400420.

It is not an unprimeable number, because it can be changed into a prime (664400423) 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, 25280 + ... + 44360.

It is an arithmetic number, because the mean of its divisors is an integer number (58171477).

Almost surely, 2^664400420 is an apocalyptic number.

It is an amenable number.

664400420 is an abundant number, since it is smaller than the sum of its proper divisors (731715028).

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

664400420 is a wasteful number, since it uses less digits than its factorization.

664400420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20831 (or 20829 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 26.

The square root of 664400420 is about 25775.9659372835. The cubic root of 664400420 is about 872.5894665553.

Adding to 664400420 its reverse (24004466), we get a palindrome (688404886).

The spelling of 664400420 in words is "six hundred sixty-four million, four hundred thousand, four hundred twenty".