20821846321 has 2 divisors, whose sum is σ = 20821846322. Its totient is φ = 20821846320.

The previous prime is 20821846319. The next prime is 20821846343. The reversal of 20821846321 is 12364812802.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19345749921 + 1476096400 = 139089^2 + 38420^2 .

It is a cyclic number.

It is not a de Polignac number, because 20821846321 - 2¹ = 20821846319 is a prime.

Together with 20821846319, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20821846301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10410923160 + 10410923161.

It is an arithmetic number, because the mean of its divisors is an integer number (10410923161).

Almost surely, 2^20821846321 is an apocalyptic number.

It is an amenable number.

20821846321 is a deficient number, since it is larger than the sum of its proper divisors (1).

20821846321 is an equidigital number, since it uses as much as digits as its factorization.

20821846321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36864, while the sum is 37.

The spelling of 20821846321 in words is "twenty billion, eight hundred twenty-one million, eight hundred forty-six thousand, three hundred twenty-one".