1221310321 has 16 divisors (see below), whose sum is σ = 1575181440. Its totient is φ = 918852480.

The previous prime is 1221310309. The next prime is 1221310331. The reversal of 1221310321 is 1230131221.

It is not a de Polignac number, because 1221310321 - 2⁵ = 1221310289 is a prime.

It is a super-2 number, since 2×1221310321² = 2983197800362246082, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221310295 and 1221310304.

It is not an unprimeable number, because it can be changed into a prime (1221310301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 271236 + ... + 275701.

It is an arithmetic number, because the mean of its divisors is an integer number (98448840).

Almost surely, 2^1221310321 is an apocalyptic number.

1221310321 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221310321 is a deficient number, since it is larger than the sum of its proper divisors (353871119).

1221310321 is a wasteful number, since it uses less digits than its factorization.

1221310321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546984.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 1221310321 is about 34947.2505499360. The cubic root of 1221310321 is about 1068.9121388882.

Adding to 1221310321 its reverse (1230131221), we get a palindrome (2451441542).

Subtracting 1221310321 from its reverse (1230131221), we obtain a square (8820900 = 2970²).

The spelling of 1221310321 in words is "one billion, two hundred twenty-one million, three hundred ten thousand, three hundred twenty-one".