20021851 has 2 divisors, whose sum is σ = 20021852. Its totient is φ = 20021850.

The previous prime is 20021849. The next prime is 20021873. The reversal of 20021851 is 15812002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20021851 - 2¹ = 20021849 is a prime.

Together with 20021849, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20021821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010925 + 10010926.

It is an arithmetic number, because the mean of its divisors is an integer number (10010926).

Almost surely, 2^20021851 is an apocalyptic number.

20021851 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021851 is an equidigital number, since it uses as much as digits as its factorization.

20021851 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 20021851 is about 4474.5783041534. The cubic root of 20021851 is about 271.5405802457.

Adding to 20021851 its reverse (15812002), we get a palindrome (35833853).

The spelling of 20021851 in words is "twenty million, twenty-one thousand, eight hundred fifty-one".