1999421779 has 2 divisors, whose sum is σ = 1999421780. Its totient is φ = 1999421778.

The previous prime is 1999421761. The next prime is 1999421797. The reversal of 1999421779 is 9771249991.

Together with next prime (1999421797) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (1999421761) and next prime (1999421797).

It is a cyclic number.

It is not a de Polignac number, because 1999421779 - 2²⁷ = 1865204051 is a prime.

It is not a weakly prime, because it can be changed into another prime (1999428779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999710889 + 999710890.

It is an arithmetic number, because the mean of its divisors is an integer number (999710890).

Almost surely, 2^1999421779 is an apocalyptic number.

1999421779 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999421779 is an equidigital number, since it uses as much as digits as its factorization.

1999421779 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 1999421779 is about 44714.8943753645. The cubic root of 1999421779 is about 1259.7996193903.

The spelling of 1999421779 in words is "one billion, nine hundred ninety-nine million, four hundred twenty-one thousand, seven hundred seventy-nine".