1331331221 has 16 divisors (see below), whose sum is σ = 1491499008. Its totient is φ = 1178049600.

The previous prime is 1331331193. The next prime is 1331331227. The reversal of 1331331221 is 1221331331.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1331331221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1331331193 and 1331331202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1331331227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 65051 + ... + 83031.

It is an arithmetic number, because the mean of its divisors is an integer number (93218688).

Almost surely, 2^1331331221 is an apocalyptic number.

1331331221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1331331221 is a deficient number, since it is larger than the sum of its proper divisors (160167787).

1331331221 is a wasteful number, since it uses less digits than its factorization.

1331331221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18172.

The product of its digits is 324, while the sum is 20.

The square root of 1331331221 is about 36487.4118155837. The cubic root of 1331331221 is about 1100.0912378867.

Adding to 1331331221 its reverse (1221331331), we get a palindrome (2552662552).

The spelling of 1331331221 in words is "one billion, three hundred thirty-one million, three hundred thirty-one thousand, two hundred twenty-one".