1221105521 has 8 divisors (see below), whose sum is σ = 1226605824. Its totient is φ = 1215617760.

The previous prime is 1221105493. The next prime is 1221105539. The reversal of 1221105521 is 1255011221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221105521 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221105493 and 1221105502.

It is not an unprimeable number, because it can be changed into a prime (1221105541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 228941 + ... + 234213.

It is an arithmetic number, because the mean of its divisors is an integer number (153325728).

Almost surely, 2^1221105521 is an apocalyptic number.

It is an amenable number.

1221105521 is a deficient number, since it is larger than the sum of its proper divisors (5500303).

1221105521 is an equidigital number, since it uses as much as digits as its factorization.

1221105521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6271.

The product of its (nonzero) digits is 200, while the sum is 20.

The square root of 1221105521 is about 34944.3202967235. The cubic root of 1221105521 is about 1068.8523873683.

Adding to 1221105521 its reverse (1255011221), we get a palindrome (2476116742).

The spelling of 1221105521 in words is "one billion, two hundred twenty-one million, one hundred five thousand, five hundred twenty-one".