221212005 has 16 divisors (see below), whose sum is σ = 404502144. Its totient is φ = 101125440.

The previous prime is 221211989. The next prime is 221212009. The reversal of 221212005 is 500212122.

It is not a de Polignac number, because 221212005 - 2⁴ = 221211989 is a prime.

It is a super-2 number, since 2×221212005² = 97869502312240050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221212009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1053286 + ... + 1053495.

It is an arithmetic number, because the mean of its divisors is an integer number (25281384).

Almost surely, 2^221212005 is an apocalyptic number.

It is an amenable number.

221212005 is a deficient number, since it is larger than the sum of its proper divisors (183290139).

221212005 is a wasteful number, since it uses less digits than its factorization.

221212005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2106796.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 221212005 is about 14873.1975378531. The cubic root of 221212005 is about 604.7876266636.

Adding to 221212005 its reverse (500212122), we get a palindrome (721424127).

It can be divided in two parts, 221 and 212005, that added together give a triangular number (212226 = T₆₅₁).

The spelling of 221212005 in words is "two hundred twenty-one million, two hundred twelve thousand, five".