1221105405 has 16 divisors (see below), whose sum is σ = 2104058880. Its totient is φ = 601159488.

The previous prime is 1221105377. The next prime is 1221105421. The reversal of 1221105405 is 5045011221.

1221105405 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1221105405 - 2⁵ = 1221105373 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3130845 + ... + 3131234.

It is an arithmetic number, because the mean of its divisors is an integer number (131503680).

Almost surely, 2^1221105405 is an apocalyptic number.

1221105405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221105405 is a deficient number, since it is larger than the sum of its proper divisors (882953475).

1221105405 is a wasteful number, since it uses less digits than its factorization.

1221105405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6262100.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 1221105405 is about 34944.3186369401. The cubic root of 1221105405 is about 1068.8523535228.

Adding to 1221105405 its reverse (5045011221), we get a palindrome (6266116626).

The spelling of 1221105405 in words is "one billion, two hundred twenty-one million, one hundred five thousand, four hundred five".