1221311206 has 4 divisors (see below), whose sum is σ = 1831966812. Its totient is φ = 610655602.

The previous prime is 1221311159. The next prime is 1221311209. The reversal of 1221311206 is 6021131221.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221311209) 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 as a sum of consecutive naturals, namely, 305327800 + ... + 305327803.

It is an arithmetic number, because the mean of its divisors is an integer number (457991703).

Almost surely, 2^1221311206 is an apocalyptic number.

1221311206 is a deficient number, since it is larger than the sum of its proper divisors (610655606).

1221311206 is an equidigital number, since it uses as much as digits as its factorization.

1221311206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610655605.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 1221311206 is about 34947.2632118740. The cubic root of 1221311206 is about 1068.9123970773.

Adding to 1221311206 its reverse (6021131221), we get a palindrome (7242442427).

The spelling of 1221311206 in words is "one billion, two hundred twenty-one million, three hundred eleven thousand, two hundred six".