1321305666 has 16 divisors (see below), whose sum is σ = 2653142688. Its totient is φ = 438680000.

The previous prime is 1321305571. The next prime is 1321305683. The reversal of 1321305666 is 6665031231.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 437175 + ... + 440186.

It is an arithmetic number, because the mean of its divisors is an integer number (165821418).

Almost surely, 2^1321305666 is an apocalyptic number.

1321305666 is an abundant number, since it is smaller than the sum of its proper divisors (1331837022).

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

1321305666 is a wasteful number, since it uses less digits than its factorization.

1321305666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 877617.

The product of its (nonzero) digits is 19440, while the sum is 33.

The square root of 1321305666 is about 36349.7684449296. The cubic root of 1321305666 is about 1097.3228744028.

Adding to 1321305666 its reverse (6665031231), we get a palindrome (7986336897).

The spelling of 1321305666 in words is "one billion, three hundred twenty-one million, three hundred five thousand, six hundred sixty-six".