19980021 has 12 divisors (see below), whose sum is σ = 26967552. Its totient is φ = 13157424.

The previous prime is 19980019. The next prime is 19980041. The reversal of 19980021 is 12008991.

It is not a de Polignac number, because 19980021 - 2¹ = 19980019 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19980041) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 87135 + ... + 87363.

It is an arithmetic number, because the mean of its divisors is an integer number (2247296).

Almost surely, 2^19980021 is an apocalyptic number.

It is an amenable number.

19980021 is a deficient number, since it is larger than the sum of its proper divisors (6987531).

19980021 is an equidigital number, since it uses as much as digits as its factorization.

19980021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588 (or 359 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 19980021 is about 4469.9016767710. The cubic root of 19980021 is about 271.3513459633.

The spelling of 19980021 in words is "nineteen million, nine hundred eighty thousand, twenty-one".