1989211421 has 2 divisors, whose sum is σ = 1989211422. Its totient is φ = 1989211420.

The previous prime is 1989211387. The next prime is 1989211447. The reversal of 1989211421 is 1241129891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1838265625 + 150945796 = 42875^2 + 12286^2 .

It is a cyclic number.

It is not a de Polignac number, because 1989211421 - 2¹⁰ = 1989210397 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1989211481) 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, 994605710 + 994605711.

It is an arithmetic number, because the mean of its divisors is an integer number (994605711).

Almost surely, 2^1989211421 is an apocalyptic number.

It is an amenable number.

1989211421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1989211421 is an equidigital number, since it uses as much as digits as its factorization.

1989211421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 38.

The square root of 1989211421 is about 44600.5764648844. The cubic root of 1989211421 is about 1257.6515044981.

It can be divided in two parts, 19892 and 11421, that added together give a palindrome (31313).

The spelling of 1989211421 in words is "one billion, nine hundred eighty-nine million, two hundred eleven thousand, four hundred twenty-one".