1313131221 has 24 divisors (see below), whose sum is σ = 2062606104. Its totient is φ = 801653760.

The previous prime is 1313131219. The next prime is 1313131243. The reversal of 1313131221 is 1221313131.

1313131221 is a `hidden beast` number, since 1 + 313 + 131 + 221 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 718990596 + 594140625 = 26814^2 + 24375^2 .

It is not a de Polignac number, because 1313131221 - 2¹ = 1313131219 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1313131194 and 1313131203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1313131271) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 110320 + ... + 121641.

It is an arithmetic number, because the mean of its divisors is an integer number (85941921).

Almost surely, 2^1313131221 is an apocalyptic number.

It is an amenable number.

1313131221 is a deficient number, since it is larger than the sum of its proper divisors (749474883).

1313131221 is a wasteful number, since it uses less digits than its factorization.

1313131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232021 (or 232018 counting only the distinct ones).

The product of its digits is 108, while the sum is 18.

The square root of 1313131221 is about 36237.1524957467. The cubic root of 1313131221 is about 1095.0552771244.

Adding to 1313131221 its reverse (1221313131), we get a palindrome (2534444352).

The spelling of 1313131221 in words is "one billion, three hundred thirteen million, one hundred thirty-one thousand, two hundred twenty-one".