1999421797 has 2 divisors, whose sum is σ = 1999421798. Its totient is φ = 1999421796.

The previous prime is 1999421779. The next prime is 1999421821. The reversal of 1999421797 is 7971249991.

Together with previous prime (1999421779) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1643005156 + 356416641 = 40534^2 + 18879^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999421797 - 2¹¹ = 1999419749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999421497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999710898 + 999710899.

It is an arithmetic number, because the mean of its divisors is an integer number (999710899).

Almost surely, 2^1999421797 is an apocalyptic number.

It is an amenable number.

1999421797 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999421797 is an equidigital number, since it uses as much as digits as its factorization.

1999421797 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2571912, while the sum is 58.

The square root of 1999421797 is about 44714.8945766397. The cubic root of 1999421797 is about 1259.7996231708.

The spelling of 1999421797 in words is "one billion, nine hundred ninety-nine million, four hundred twenty-one thousand, seven hundred ninety-seven".