19983721 has 8 divisors (see below), whose sum is σ = 21288960. Its totient is φ = 18692928.

The previous prime is 19983709. The next prime is 19983727. The reversal of 19983721 is 12738991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 19983721 - 2²¹ = 17886569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19983727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 681 + ... + 6358.

It is an arithmetic number, because the mean of its divisors is an integer number (2661120).

Almost surely, 2^19983721 is an apocalyptic number.

It is an amenable number.

19983721 is a deficient number, since it is larger than the sum of its proper divisors (1305239).

19983721 is a wasteful number, since it uses less digits than its factorization.

19983721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7223.

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

The square root of 19983721 is about 4470.3155369616. The cubic root of 19983721 is about 271.3680949949.

The spelling of 19983721 in words is "nineteen million, nine hundred eighty-three thousand, seven hundred twenty-one".