1331225666 has 4 divisors (see below), whose sum is σ = 1996838502. Its totient is φ = 665612832.

The previous prime is 1331225659. The next prime is 1331225677. The reversal of 1331225666 is 6665221331.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6665221331 = 17 ⋅392071843.

It can be written as a sum of positive squares in only one way, i.e., 1226470441 + 104755225 = 35021^2 + 10235^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332806415 + ... + 332806418.

Almost surely, 2^1331225666 is an apocalyptic number.

1331225666 is a deficient number, since it is larger than the sum of its proper divisors (665612836).

1331225666 is an equidigital number, since it uses as much as digits as its factorization.

1331225666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 665612835.

The product of its digits is 38880, while the sum is 35.

The square root of 1331225666 is about 36485.9653291509. The cubic root of 1331225666 is about 1100.0621634291.

Adding to 1331225666 its reverse (6665221331), we get a palindrome (7996446997).

The spelling of 1331225666 in words is "one billion, three hundred thirty-one million, two hundred twenty-five thousand, six hundred sixty-six".