1221203917 has 2 divisors, whose sum is σ = 1221203918. Its totient is φ = 1221203916.

The previous prime is 1221203911. The next prime is 1221203939. The reversal of 1221203917 is 7193021221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1114825321 + 106378596 = 33389^2 + 10314^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221203917 - 2³ = 1221203909 is a prime.

It is a super-2 number, since 2×1221203917² = 2982678013792285778, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221203911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610601958 + 610601959.

It is an arithmetic number, because the mean of its divisors is an integer number (610601959).

Almost surely, 2^1221203917 is an apocalyptic number.

It is an amenable number.

1221203917 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221203917 is an equidigital number, since it uses as much as digits as its factorization.

1221203917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1512, while the sum is 28.

The square root of 1221203917 is about 34945.7281652565. The cubic root of 1221203917 is about 1068.8810957731.

The spelling of 1221203917 in words is "one billion, two hundred twenty-one million, two hundred three thousand, nine hundred seventeen".