1221321243 has 16 divisors (see below), whose sum is σ = 1675108512. Its totient is φ = 791040000.

The previous prime is 1221321239. The next prime is 1221321247. The reversal of 1221321243 is 3421231221.

It is an interprime number because it is at equal distance from previous prime (1221321239) and next prime (1221321247).

It is not a de Polignac number, because 1221321243 - 2² = 1221321239 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221321247) 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, 9043 + ... + 50243.

It is an arithmetic number, because the mean of its divisors is an integer number (104694282).

Almost surely, 2^1221321243 is an apocalyptic number.

1221321243 is a deficient number, since it is larger than the sum of its proper divisors (453787269).

1221321243 is a wasteful number, since it uses less digits than its factorization.

1221321243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41486.

The product of its digits is 576, while the sum is 21.

The square root of 1221321243 is about 34947.4068136679. The cubic root of 1221321243 is about 1068.9153252538.

Adding to 1221321243 its reverse (3421231221), we get a palindrome (4642552464).

The spelling of 1221321243 in words is "one billion, two hundred twenty-one million, three hundred twenty-one thousand, two hundred forty-three".