1321999979 has 2 divisors, whose sum is σ = 1321999980. Its totient is φ = 1321999978.

The previous prime is 1321999969. The next prime is 1322000011. The reversal of 1321999979 is 9799991231.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (9799991231) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1321999979 is a prime.

It is not a weakly prime, because it can be changed into another prime (1321999919) 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, 660999989 + 660999990.

It is an arithmetic number, because the mean of its divisors is an integer number (660999990).

Almost surely, 2^1321999979 is an apocalyptic number.

1321999979 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321999979 is an equidigital number, since it uses as much as digits as its factorization.

1321999979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2480058, while the sum is 59.

The square root of 1321999979 is about 36359.3176366114. The cubic root of 1321999979 is about 1097.5150459658.

The spelling of 1321999979 in words is "one billion, three hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred seventy-nine".