1216221001 has 2 divisors, whose sum is σ = 1216221002. Its totient is φ = 1216221000.

The previous prime is 1216220939. The next prime is 1216221023. The reversal of 1216221001 is 1001226121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 969699600 + 246521401 = 31140^2 + 15701^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1216221001 is a prime.

It is not a weakly prime, because it can be changed into another prime (1216221031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608110500 + 608110501.

It is an arithmetic number, because the mean of its divisors is an integer number (608110501).

Almost surely, 2^1216221001 is an apocalyptic number.

It is an amenable number.

1216221001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216221001 is an equidigital number, since it uses as much as digits as its factorization.

1216221001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 1216221001 is about 34874.3602235224. The cubic root of 1216221001 is about 1067.4253177904.

Adding to 1216221001 its reverse (1001226121), we get a palindrome (2217447122).

The spelling of 1216221001 in words is "one billion, two hundred sixteen million, two hundred twenty-one thousand, one".