1205555021 has 16 divisors (see below), whose sum is σ = 1350518400. Its totient is φ = 1066617600.

The previous prime is 1205555003. The next prime is 1205555047.

1205555021 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 1205555021 - 2³⁰ = 131813197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1205555081) 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 15 ways as a sum of consecutive naturals, for example, 194945 + ... + 201033.

It is an arithmetic number, because the mean of its divisors is an integer number (84407400).

Almost surely, 2^1205555021 is an apocalyptic number.

1205555021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1205555021 is a deficient number, since it is larger than the sum of its proper divisors (144963379).

1205555021 is a wasteful number, since it uses less digits than its factorization.

1205555021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6580.

The product of its (nonzero) digits is 2500, while the sum is 26.

The square root of 1205555021 is about 34721.1033954856. The cubic root of 1205555021 is about 1064.2957928465.

It can be divided in two parts, 12055 and 55021, that added together give a palindrome (67076).

The spelling of 1205555021 in words is "one billion, two hundred five million, five hundred fifty-five thousand, twenty-one".