1219821917 has 2 divisors, whose sum is σ = 1219821918. Its totient is φ = 1219821916.

The previous prime is 1219821913. The next prime is 1219821923. The reversal of 1219821917 is 7191289121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 927446116 + 292375801 = 30454^2 + 17099^2 .

It is an emirp because it is prime and its reverse (7191289121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1219821917 - 2² = 1219821913 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1219821913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 609910958 + 609910959.

It is an arithmetic number, because the mean of its divisors is an integer number (609910959).

Almost surely, 2^1219821917 is an apocalyptic number.

It is an amenable number.

1219821917 is a deficient number, since it is larger than the sum of its proper divisors (1).

1219821917 is an equidigital number, since it uses as much as digits as its factorization.

1219821917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 41.

The square root of 1219821917 is about 34925.9490493816. The cubic root of 1219821917 is about 1068.4777366408.

The spelling of 1219821917 in words is "one billion, two hundred nineteen million, eight hundred twenty-one thousand, nine hundred seventeen".