1221535231 has 4 divisors (see below), whose sum is σ = 1396040272. Its totient is φ = 1047030192.

The previous prime is 1221535199. The next prime is 1221535241. The reversal of 1221535231 is 1325351221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1325351221 = 83 ⋅15968087.

It is a cyclic number.

It is not a de Polignac number, because 1221535231 - 2⁵ = 1221535199 is a prime.

It is a super-2 number, since 2×1221535231² = 2984296641148446722, 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 = 1221535196 and 1221535205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221535241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 87252510 + ... + 87252523.

It is an arithmetic number, because the mean of its divisors is an integer number (349010068).

Almost surely, 2^1221535231 is an apocalyptic number.

1221535231 is a deficient number, since it is larger than the sum of its proper divisors (174505041).

1221535231 is an equidigital number, since it uses as much as digits as its factorization.

1221535231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174505040.

The product of its digits is 1800, while the sum is 25.

The square root of 1221535231 is about 34950.4682515127. The cubic root of 1221535231 is about 1068.9777499151.

Adding to 1221535231 its reverse (1325351221), we get a palindrome (2546886452).

The spelling of 1221535231 in words is "one billion, two hundred twenty-one million, five hundred thirty-five thousand, two hundred thirty-one".