19717939 has 4 divisors (see below), whose sum is σ = 19748520. Its totient is φ = 19687360.

The previous prime is 19717937. The next prime is 19717967. The reversal of 19717939 is 93971791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93971791 = 4391 ⋅21401.

It is a cyclic number.

It is not a de Polignac number, because 19717939 - 2¹ = 19717937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19717931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14302 + ... + 15619.

It is an arithmetic number, because the mean of its divisors is an integer number (4937130).

Almost surely, 2^19717939 is an apocalyptic number.

19717939 is a deficient number, since it is larger than the sum of its proper divisors (30581).

19717939 is an equidigital number, since it uses as much as digits as its factorization.

19717939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30580.

The product of its digits is 107163, while the sum is 46.

The square root of 19717939 is about 4440.4885992422. The cubic root of 19717939 is about 270.1596632242.

The spelling of 19717939 in words is "nineteen million, seven hundred seventeen thousand, nine hundred thirty-nine".