19721983 has 4 divisors (see below), whose sum is σ = 20358208. Its totient is φ = 19085760.

The previous prime is 19721963. The next prime is 19722013. The reversal of 19721983 is 38912791.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19721983 - 2¹⁷ = 19590911 is a prime.

It is a super-2 number, since 2×19721983² = 777913226904578, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19721903) 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, 318066 + ... + 318127.

It is an arithmetic number, because the mean of its divisors is an integer number (5089552).

Almost surely, 2^19721983 is an apocalyptic number.

19721983 is a deficient number, since it is larger than the sum of its proper divisors (636225).

19721983 is an equidigital number, since it uses as much as digits as its factorization.

19721983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 636224.

The product of its digits is 27216, while the sum is 40.

The square root of 19721983 is about 4440.9439311930. The cubic root of 19721983 is about 270.1781311955.

The spelling of 19721983 in words is "nineteen million, seven hundred twenty-one thousand, nine hundred eighty-three".