20016921 has 4 divisors (see below), whose sum is σ = 26689232. Its totient is φ = 13344612.

The previous prime is 20016911. The next prime is 20016943. The reversal of 20016921 is 12961002.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20016921 - 2¹⁴ = 20000537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20016911) 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 3 ways as a sum of consecutive naturals, for example, 3336151 + ... + 3336156.

It is an arithmetic number, because the mean of its divisors is an integer number (6672308).

Almost surely, 2^20016921 is an apocalyptic number.

It is an amenable number.

20016921 is a deficient number, since it is larger than the sum of its proper divisors (6672311).

20016921 is an equidigital number, since it uses as much as digits as its factorization.

20016921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6672310.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 20016921 is about 4474.0273803364. The cubic root of 20016921 is about 271.5182911818.

Adding to 20016921 its reverse (12961002), we get a palindrome (32977923).

The spelling of 20016921 in words is "twenty million, sixteen thousand, nine hundred twenty-one".