664125520 has 80 divisors (see below), whose sum is σ = 1604428560. Its totient is φ = 255352832.

The previous prime is 664125479. The next prime is 664125533. The reversal of 664125520 is 25521466.

664125520 is digitally balanced in base 6, 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 8 ways, for example, as 142277184 + 521848336 = 11928^2 + 22844^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

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, 679272 + ... + 680248.

It is an arithmetic number, because the mean of its divisors is an integer number (20055357).

Almost surely, 2^664125520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664125520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (802214280).

664125520 is an abundant number, since it is smaller than the sum of its proper divisors (940303040).

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

664125520 is a wasteful number, since it uses less digits than its factorization.

664125520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1312 (or 1306 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 31.

The square root of 664125520 is about 25770.6328987086. The cubic root of 664125520 is about 872.4691034289.

Adding to 664125520 its reverse (25521466), we get a palindrome (689646986).

The spelling of 664125520 in words is "six hundred sixty-four million, one hundred twenty-five thousand, five hundred twenty".