660742321 has 4 divisors (see below), whose sum is σ = 689470272. Its totient is φ = 632014372.

The previous prime is 660742297. The next prime is 660742373. The reversal of 660742321 is 123247066.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 660742321 - 2⁵ = 660742289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (660742391) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14363941 + ... + 14363986.

It is an arithmetic number, because the mean of its divisors is an integer number (172367568).

Almost surely, 2^660742321 is an apocalyptic number.

It is an amenable number.

660742321 is a deficient number, since it is larger than the sum of its proper divisors (28727951).

660742321 is a wasteful number, since it uses less digits than its factorization.

660742321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28727950.

The product of its (nonzero) digits is 12096, while the sum is 31.

The square root of 660742321 is about 25704.9085001289. The cubic root of 660742321 is about 870.9850651438.

Adding to 660742321 its reverse (123247066), we get a palindrome (783989387).

The spelling of 660742321 in words is "six hundred sixty million, seven hundred forty-two thousand, three hundred twenty-one".