1221313231 has 4 divisors (see below), whose sum is σ = 1260710464. Its totient is φ = 1181916000.

The previous prime is 1221313213. The next prime is 1221313237. The reversal of 1221313231 is 1323131221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1323131221 = 71 ⋅18635651.

It is a cyclic number.

It is not a de Polignac number, because 1221313231 - 2¹³ = 1221305039 is a prime.

It is a super-2 number, since 2×1221313231² = 2983212016431318722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221313199 and 1221313208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221313237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19698570 + ... + 19698631.

It is an arithmetic number, because the mean of its divisors is an integer number (315177616).

Almost surely, 2^1221313231 is an apocalyptic number.

1221313231 is a deficient number, since it is larger than the sum of its proper divisors (39397233).

1221313231 is an equidigital number, since it uses as much as digits as its factorization.

1221313231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39397232.

The product of its digits is 216, while the sum is 19.

The square root of 1221313231 is about 34947.2921840877. The cubic root of 1221313231 is about 1068.9129878485.

Adding to 1221313231 its reverse (1323131221), we get a palindrome (2544444452).

The spelling of 1221313231 in words is "one billion, two hundred twenty-one million, three hundred thirteen thousand, two hundred thirty-one".