664580826 has 144 divisors (see below), whose sum is σ = 1820637000. Its totient is φ = 173650176.

The previous prime is 664580797. The next prime is 664580869. The reversal of 664580826 is 628085466.

664580826 is a `hidden beast` number, since 6 + 64 + 580 + 8 + 2 + 6 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 227979801 + 436601025 = 15099^2 + 20895^2 .

It is a super-5 number, since 5×664580826⁵ (a number of 45 digits) contains 55555 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1708240 + ... + 1708628.

Almost surely, 2^664580826 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664580826, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (910318500).

664580826 is an abundant number, since it is smaller than the sum of its proper divisors (1156056174).

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

664580826 is a wasteful number, since it uses less digits than its factorization.

664580826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 573 (or 563 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 45.

The square root of 664580826 is about 25779.4652000386. The cubic root of 664580826 is about 872.6684380733.

The spelling of 664580826 in words is "six hundred sixty-four million, five hundred eighty thousand, eight hundred twenty-six".