19995979 has 2 divisors, whose sum is σ = 19995980. Its totient is φ = 19995978.

The previous prime is 19995973. The next prime is 19996001. The reversal of 19995979 is 97959991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19995979 - 2⁷ = 19995851 is a prime.

It is not a weakly prime, because it can be changed into another prime (19995973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9997989 + 9997990.

It is an arithmetic number, because the mean of its divisors is an integer number (9997990).

Almost surely, 2^19995979 is an apocalyptic number.

19995979 is a deficient number, since it is larger than the sum of its proper divisors (1).

19995979 is an equidigital number, since it uses as much as digits as its factorization.

19995979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2066715, while the sum is 58.

The square root of 19995979 is about 4471.6863709343. The cubic root of 19995979 is about 271.4235693182.

The spelling of 19995979 in words is "nineteen million, nine hundred ninety-five thousand, nine hundred seventy-nine".