660388321 has 8 divisors (see below), whose sum is σ = 691035624. Its totient is φ = 630414720.

The previous prime is 660388297. The next prime is 660388331. The reversal of 660388321 is 123883066.

It can be written as a sum of positive squares in 4 ways, for example, as 521619921 + 138768400 = 22839^2 + 11780^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 660388321 - 2⁷ = 660388193 is a prime.

It is a super-2 number, since 2×660388321² = 872225469026398082, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (660388331) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 166420 + ... + 170341.

It is an arithmetic number, because the mean of its divisors is an integer number (86379453).

Almost surely, 2^660388321 is an apocalyptic number.

It is an amenable number.

660388321 is a deficient number, since it is larger than the sum of its proper divisors (30647303).

660388321 is a wasteful number, since it uses less digits than its factorization.

660388321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336851.

The product of its (nonzero) digits is 41472, while the sum is 37.

The square root of 660388321 is about 25698.0217331996. The cubic root of 660388321 is about 870.8294907324.

The spelling of 660388321 in words is "six hundred sixty million, three hundred eighty-eight thousand, three hundred twenty-one".