581321664 has 448 divisors, whose sum is σ = 2264785920. Its totient is φ = 141557760.

The previous prime is 581321623. The next prime is 581321707. The reversal of 581321664 is 466123185.

It is a happy number.

581321664 is a `hidden beast` number, since 581 + 3 + 2 + 16 + 64 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2261824 + ... + 2262080.

Almost surely, 2^581321664 is an apocalyptic number.

581321664 is a gapful number since it is divisible by the number (54) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 581321664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1132392960).

581321664 is an abundant number, since it is smaller than the sum of its proper divisors (1683464256).

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

581321664 is a wasteful number, since it uses less digits than its factorization.

581321664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313 (or 297 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 581321664 is about 24110.6130987995. The cubic root of 581321664 is about 834.5880641082.

The spelling of 581321664 in words is "five hundred eighty-one million, three hundred twenty-one thousand, six hundred sixty-four".