19785979 has 2 divisors, whose sum is σ = 19785980. Its totient is φ = 19785978.

The previous prime is 19785949. The next prime is 19786027. The reversal of 19785979 is 97958791.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19785979 - 2⁷ = 19785851 is a prime.

It is not a weakly prime, because it can be changed into another prime (19785949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9892989 + 9892990.

It is an arithmetic number, because the mean of its divisors is an integer number (9892990).

Almost surely, 2^19785979 is an apocalyptic number.

19785979 is a deficient number, since it is larger than the sum of its proper divisors (1).

19785979 is an equidigital number, since it uses as much as digits as its factorization.

19785979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1428840, while the sum is 55.

The square root of 19785979 is about 4448.1433205327. The cubic root of 19785979 is about 270.4700499730.

The spelling of 19785979 in words is "nineteen million, seven hundred eighty-five thousand, nine hundred seventy-nine".