1221213305 has 16 divisors (see below), whose sum is σ = 1620840144. Its totient is φ = 877443840.

The previous prime is 1221213293. The next prime is 1221213311. The reversal of 1221213305 is 5033121221.

It can be written as a sum of positive squares in 8 ways, for example, as 44448889 + 1176764416 = 6667^2 + 34304^2 .

It is not a de Polignac number, because 1221213305 - 2⁴ = 1221213289 is a prime.

It is a Duffinian 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, 251486 + ... + 256295.

It is an arithmetic number, because the mean of its divisors is an integer number (101302509).

Almost surely, 2^1221213305 is an apocalyptic number.

It is an amenable number.

1221213305 is a deficient number, since it is larger than the sum of its proper divisors (399626839).

1221213305 is a wasteful number, since it uses less digits than its factorization.

1221213305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507836.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 1221213305 is about 34945.8624875678. The cubic root of 1221213305 is about 1068.8838347724.

Adding to 1221213305 its reverse (5033121221), we get a palindrome (6254334526).

The spelling of 1221213305 in words is "one billion, two hundred twenty-one million, two hundred thirteen thousand, three hundred five".