664131220 has 24 divisors (see below), whose sum is σ = 1403918208. Its totient is φ = 263892000.

The previous prime is 664131211. The next prime is 664131227. The reversal of 664131220 is 22131466.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664131227) 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, 106936 + ... + 112975.

It is an arithmetic number, because the mean of its divisors is an integer number (58496592).

Almost surely, 2^664131220 is an apocalyptic number.

It is an amenable number.

664131220 is an abundant number, since it is smaller than the sum of its proper divisors (739786988).

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

664131220 is a wasteful number, since it uses less digits than its factorization.

664131220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220071 (or 220069 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 664131220 is about 25770.7434894688. The cubic root of 664131220 is about 872.4715994729.

Adding to 664131220 its reverse (22131466), we get a palindrome (686262686).

The spelling of 664131220 in words is "six hundred sixty-four million, one hundred thirty-one thousand, two hundred twenty".